diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index b73a41309..4515fadea 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -82,6 +82,7 @@ updates:
       - "/src/Instrumentation/Psr18"
       - "/src/Instrumentation/Psr3"
       - "/src/Instrumentation/Psr6"
+      - "/src/Instrumentation/ReactPHP"
       - "/src/Instrumentation/Slim"
       - "/src/Instrumentation/Symfony"
       - "/src/Instrumentation/Wordpress"
diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index 601a3f5d0..769e89061 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -43,6 +43,7 @@ jobs:
           'Instrumentation/Psr15',
           'Instrumentation/Psr16',
           'Instrumentation/Psr18',
+          'Instrumentation/ReactPHP',
           'Instrumentation/Slim',
           'Instrumentation/Symfony',
           'Instrumentation/Yii',
diff --git a/.gitsplit.yml b/.gitsplit.yml
index 072982784..e6268eaaa 100644
--- a/.gitsplit.yml
+++ b/.gitsplit.yml
@@ -48,6 +48,8 @@ splits:
     target: "https://${GH_TOKEN}@github.com/opentelemetry-php/contrib-auto-psr16.git"
   - prefix: "src/Instrumentation/Psr18"
     target: "https://${GH_TOKEN}@github.com/opentelemetry-php/contrib-auto-psr18.git"
+  - prefix: "src/Instrumentation/ReactPHP"
+    target: "https://${GH_TOKEN}@github.com/opentelemetry-php/contrib-auto-reactphp.git"
   - prefix: "src/Instrumentation/Slim"
     target: "https://${GH_TOKEN}@github.com/opentelemetry-php/contrib-auto-slim.git"
   - prefix: "src/Instrumentation/Symfony"
diff --git a/composer.json b/composer.json
index 363615182..6155e0978 100644
--- a/composer.json
+++ b/composer.json
@@ -29,6 +29,7 @@
       "OpenTelemetry\\Contrib\\Instrumentation\\Psr3\\": "src/Instrumentation/Psr3/src",
       "OpenTelemetry\\Contrib\\Instrumentation\\Psr15\\": "src/Instrumentation/Psr15/src",
       "OpenTelemetry\\Contrib\\Instrumentation\\Psr18\\": "src/Instrumentation/Psr18/src",
+      "OpenTelemetry\\Contrib\\Instrumentation\\ReactPHP\\": "src/Instrumentation/ReactPHP/src",
       "OpenTelemetry\\Contrib\\Instrumentation\\Slim\\": "src/Instrumentation/Slim/src",
       "OpenTelemetry\\Contrib\\Instrumentation\\Symfony\\": "src/Instrumentation/Symfony/src",
       "OpenTelemetry\\Contrib\\Instrumentation\\Wordpress\\": "src/Instrumentation/Wordpress/src",
@@ -53,6 +54,7 @@
       "src/Instrumentation/Psr3/_register.php",
       "src/Instrumentation/Psr15/_register.php",
       "src/Instrumentation/Psr18/_register.php",
+      "src/Instrumentation/ReactPHP/_register.php",
       "src/Instrumentation/Slim/_register.php",
       "src/Instrumentation/Symfony/_register.php",
       "src/Instrumentation/Wordpress/_register.php",
@@ -79,6 +81,7 @@
     "open-telemetry/opentelemetry-auto-psr3": "self.version",
     "open-telemetry/opentelemetry-auto-psr15": "self.version",
     "open-telemetry/opentelemetry-auto-psr18": "self.version",
+    "open-telemetry/opentelemetry-auto-reactphp": "self.version",
     "open-telemetry/opentelemetry-auto-slim": "self.version",
     "open-telemetry/opentelemetry-auto-symfony": "self.version",
     "open-telemetry/opentelemetry-auto-wordpress": "self.version",
diff --git a/src/Instrumentation/ReactPHP/.gitattributes b/src/Instrumentation/ReactPHP/.gitattributes
new file mode 100644
index 000000000..ed9722120
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/.gitattributes
@@ -0,0 +1,14 @@
+* text=auto
+
+*.md diff=markdown
+*.php diff=php
+
+/.gitattributes export-ignore
+/.gitignore export-ignore
+/.phan export-ignore
+/.php-cs-fixer.php export-ignore
+/examples export-ignore
+/phpstan.neon.dist export-ignore
+/phpunit.xml.dist export-ignore
+/psalm.xml.dist export-ignore
+/tests export-ignore
diff --git a/src/Instrumentation/ReactPHP/.gitignore b/src/Instrumentation/ReactPHP/.gitignore
new file mode 100644
index 000000000..57872d0f1
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/.gitignore
@@ -0,0 +1 @@
+/vendor/
diff --git a/src/Instrumentation/ReactPHP/.phan/config.php b/src/Instrumentation/ReactPHP/.phan/config.php
new file mode 100644
index 000000000..da2ac2d99
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/.phan/config.php
@@ -0,0 +1,371 @@
+<?php
+
+use Phan\Issue;
+
+/**
+ * This configuration file was automatically generated by 'phan --init --init-level=3'
+ *
+ * TODOs (added by 'phan --init'):
+ *
+ * - Go through this file and verify that there are no missing/unnecessary files/directories.
+ *   (E.g. this only includes direct composer dependencies - You may have to manually add indirect composer dependencies to 'directory_list')
+ * - Look at 'plugins' and add or remove plugins if appropriate (see https://github.com/phan/phan/tree/master/.phan/plugins#plugins)
+ * - Add global suppressions for pre-existing issues to suppress_issue_types (https://github.com/phan/phan/wiki/Tutorial-for-Analyzing-a-Large-Sloppy-Code-Base)
+ *
+ * This configuration will be read and overlaid on top of the
+ * default configuration. Command line arguments will be applied
+ * after this file is read.
+ *
+ * @see src/Phan/Config.php
+ * See Config for all configurable options.
+ *
+ * A Note About Paths
+ * ==================
+ *
+ * Files referenced from this file should be defined as
+ *
+ * ```
+ *   Config::projectPath('relative_path/to/file')
+ * ```
+ *
+ * where the relative path is relative to the root of the
+ * project which is defined as either the working directory
+ * of the phan executable or a path passed in via the CLI
+ * '-d' flag.
+ */
+return [
+
+    // Supported values: `'5.6'`, `'7.0'`, `'7.1'`, `'7.2'`, `'7.3'`, `'7.4'`, `null`.
+    // If this is set to `null`,
+    // then Phan assumes the PHP version which is closest to the minor version
+    // of the php executable used to execute Phan.
+    //
+    // Note that the **only** effect of choosing `'5.6'` is to infer that functions removed in php 7.0 exist.
+    // (See `backward_compatibility_checks` for additional options)
+    'target_php_version' => '8.0',
+
+    // If enabled, missing properties will be created when
+    // they are first seen. If false, we'll report an
+    // error message if there is an attempt to write
+    // to a class property that wasn't explicitly
+    // defined.
+    'allow_missing_properties' => false,
+
+    // If enabled, null can be cast to any type and any
+    // type can be cast to null. Setting this to true
+    // will cut down on false positives.
+    'null_casts_as_any_type' => false,
+
+    // If enabled, allow null to be cast as any array-like type.
+    //
+    // This is an incremental step in migrating away from `null_casts_as_any_type`.
+    // If `null_casts_as_any_type` is true, this has no effect.
+    'null_casts_as_array' => true,
+
+    // If enabled, allow any array-like type to be cast to null.
+    // This is an incremental step in migrating away from `null_casts_as_any_type`.
+    // If `null_casts_as_any_type` is true, this has no effect.
+    'array_casts_as_null' => true,
+
+    // If enabled, scalars (int, float, bool, string, null)
+    // are treated as if they can cast to each other.
+    // This does not affect checks of array keys. See `scalar_array_key_cast`.
+    'scalar_implicit_cast' => false,
+
+    // If enabled, any scalar array keys (int, string)
+    // are treated as if they can cast to each other.
+    // E.g. `array<int,stdClass>` can cast to `array<string,stdClass>` and vice versa.
+    // Normally, a scalar type such as int could only cast to/from int and mixed.
+    'scalar_array_key_cast' => true,
+
+    // If this has entries, scalars (int, float, bool, string, null)
+    // are allowed to perform the casts listed.
+    //
+    // E.g. `['int' => ['float', 'string'], 'float' => ['int'], 'string' => ['int'], 'null' => ['string']]`
+    // allows casting null to a string, but not vice versa.
+    // (subset of `scalar_implicit_cast`)
+    'scalar_implicit_partial' => [],
+
+    // If enabled, Phan will warn if **any** type in a method invocation's object
+    // is definitely not an object,
+    // or if **any** type in an invoked expression is not a callable.
+    // Setting this to true will introduce numerous false positives
+    // (and reveal some bugs).
+    'strict_method_checking' => false,
+
+    // If enabled, Phan will warn if **any** type of the object expression for a property access
+    // does not contain that property.
+    'strict_object_checking' => false,
+
+    // If enabled, Phan will warn if **any** type in the argument's union type
+    // cannot be cast to a type in the parameter's expected union type.
+    // Setting this to true will introduce numerous false positives
+    // (and reveal some bugs).
+    'strict_param_checking' => false,
+
+    // If enabled, Phan will warn if **any** type in a property assignment's union type
+    // cannot be cast to a type in the property's declared union type.
+    // Setting this to true will introduce numerous false positives
+    // (and reveal some bugs).
+    'strict_property_checking' => false,
+
+    // If enabled, Phan will warn if **any** type in a returned value's union type
+    // cannot be cast to the declared return type.
+    // Setting this to true will introduce numerous false positives
+    // (and reveal some bugs).
+    'strict_return_checking' => false,
+
+    // If true, seemingly undeclared variables in the global
+    // scope will be ignored.
+    //
+    // This is useful for projects with complicated cross-file
+    // globals that you have no hope of fixing.
+    'ignore_undeclared_variables_in_global_scope' => true,
+
+    // Set this to false to emit `PhanUndeclaredFunction` issues for internal functions that Phan has signatures for,
+    // but aren't available in the codebase, or from Reflection.
+    // (may lead to false positives if an extension isn't loaded)
+    //
+    // If this is true(default), then Phan will not warn.
+    //
+    // Even when this is false, Phan will still infer return values and check parameters of internal functions
+    // if Phan has the signatures.
+    'ignore_undeclared_functions_with_known_signatures' => true,
+
+    // Backwards Compatibility Checking. This is slow
+    // and expensive, but you should consider running
+    // it before upgrading your version of PHP to a
+    // new version that has backward compatibility
+    // breaks.
+    //
+    // If you are migrating from PHP 5 to PHP 7,
+    // you should also look into using
+    // [php7cc (no longer maintained)](https://github.com/sstalle/php7cc)
+    // and [php7mar](https://github.com/Alexia/php7mar),
+    // which have different backwards compatibility checks.
+    'backward_compatibility_checks' => false,
+
+    // If true, check to make sure the return type declared
+    // in the doc-block (if any) matches the return type
+    // declared in the method signature.
+    'check_docblock_signature_return_type_match' => false,
+
+    // If true, make narrowed types from phpdoc params override
+    // the real types from the signature, when real types exist.
+    // (E.g. allows specifying desired lists of subclasses,
+    //  or to indicate a preference for non-nullable types over nullable types)
+    //
+    // Affects analysis of the body of the method and the param types passed in by callers.
+    //
+    // (*Requires `check_docblock_signature_param_type_match` to be true*)
+    'prefer_narrowed_phpdoc_param_type' => true,
+
+    // (*Requires `check_docblock_signature_return_type_match` to be true*)
+    //
+    // If true, make narrowed types from phpdoc returns override
+    // the real types from the signature, when real types exist.
+    //
+    // (E.g. allows specifying desired lists of subclasses,
+    // or to indicate a preference for non-nullable types over nullable types)
+    //
+    // This setting affects the analysis of return statements in the body of the method and the return types passed in by callers.
+    'prefer_narrowed_phpdoc_return_type' => true,
+
+    // If enabled, check all methods that override a
+    // parent method to make sure its signature is
+    // compatible with the parent's.
+    //
+    // This check can add quite a bit of time to the analysis.
+    //
+    // This will also check if final methods are overridden, etc.
+    'analyze_signature_compatibility' => true,
+
+    // This setting maps case-insensitive strings to union types.
+    //
+    // This is useful if a project uses phpdoc that differs from the phpdoc2 standard.
+    //
+    // If the corresponding value is the empty string,
+    // then Phan will ignore that union type (E.g. can ignore 'the' in `@return the value`)
+    //
+    // If the corresponding value is not empty,
+    // then Phan will act as though it saw the corresponding UnionTypes(s)
+    // when the keys show up in a UnionType of `@param`, `@return`, `@var`, `@property`, etc.
+    //
+    // This matches the **entire string**, not parts of the string.
+    // (E.g. `@return the|null` will still look for a class with the name `the`, but `@return the` will be ignored with the below setting)
+    //
+    // (These are not aliases, this setting is ignored outside of doc comments).
+    // (Phan does not check if classes with these names exist)
+    //
+    // Example setting: `['unknown' => '', 'number' => 'int|float', 'char' => 'string', 'long' => 'int', 'the' => '']`
+    'phpdoc_type_mapping' => [],
+
+    // Set to true in order to attempt to detect dead
+    // (unreferenced) code. Keep in mind that the
+    // results will only be a guess given that classes,
+    // properties, constants and methods can be referenced
+    // as variables (like `$class->$property` or
+    // `$class->$method()`) in ways that we're unable
+    // to make sense of.
+    'dead_code_detection' => false,
+
+    // Set to true in order to attempt to detect unused variables.
+    // `dead_code_detection` will also enable unused variable detection.
+    //
+    // This has a few known false positives, e.g. for loops or branches.
+    'unused_variable_detection' => false,
+
+    // Set to true in order to attempt to detect redundant and impossible conditions.
+    //
+    // This has some false positives involving loops,
+    // variables set in branches of loops, and global variables.
+    'redundant_condition_detection' => false,
+
+    // If enabled, Phan will act as though it's certain of real return types of a subset of internal functions,
+    // even if those return types aren't available in reflection (real types were taken from php 7.3 or 8.0-dev, depending on target_php_version).
+    //
+    // Note that with php 7 and earlier, php would return null or false for many internal functions if the argument types or counts were incorrect.
+    // As a result, enabling this setting with target_php_version 8.0 may result in false positives for `--redundant-condition-detection` when codebases also support php 7.x.
+    'assume_real_types_for_internal_functions' => false,
+
+    // If true, this runs a quick version of checks that takes less
+    // time at the cost of not running as thorough
+    // of an analysis. You should consider setting this
+    // to true only when you wish you had more **undiagnosed** issues
+    // to fix in your code base.
+    //
+    // In quick-mode the scanner doesn't rescan a function
+    // or a method's code block every time a call is seen.
+    // This means that the problem here won't be detected:
+    //
+    // ```php
+    // <?php
+    // function test($arg):int {
+    //     return $arg;
+    // }
+    // test("abc");
+    // ```
+    //
+    // This would normally generate:
+    //
+    // ```
+    // test.php:3 PhanTypeMismatchReturn Returning type string but test() is declared to return int
+    // ```
+    //
+    // The initial scan of the function's code block has no
+    // type information for `$arg`. It isn't until we see
+    // the call and rescan `test()`'s code block that we can
+    // detect that it is actually returning the passed in
+    // `string` instead of an `int` as declared.
+    'quick_mode' => false,
+
+    // Enable or disable support for generic templated
+    // class types.
+    'generic_types_enabled' => true,
+
+    // Override to hardcode existence and types of (non-builtin) globals in the global scope.
+    // Class names should be prefixed with `\`.
+    //
+    // (E.g. `['_FOO' => '\FooClass', 'page' => '\PageClass', 'userId' => 'int']`)
+    'globals_type_map' => [],
+
+    // The minimum severity level to report on. This can be
+    // set to `Issue::SEVERITY_LOW`, `Issue::SEVERITY_NORMAL` or
+    // `Issue::SEVERITY_CRITICAL`. Setting it to only
+    // critical issues is a good place to start on a big
+    // sloppy mature code base.
+    'minimum_severity' => Issue::SEVERITY_LOW,
+
+    // Add any issue types (such as `'PhanUndeclaredMethod'`)
+    // to this deny-list to inhibit them from being reported.
+    'suppress_issue_types' => [],
+
+    // A regular expression to match files to be excluded
+    // from parsing and analysis and will not be read at all.
+    //
+    // This is useful for excluding groups of test or example
+    // directories/files, unanalyzable files, or files that
+    // can't be removed for whatever reason.
+    // (e.g. `'@Test\.php$@'`, or `'@vendor/.*/(tests|Tests)/@'`)
+    'exclude_file_regex' => '@^vendor/.*/(tests?|Tests?)/@',
+
+    // A list of files that will be excluded from parsing and analysis
+    // and will not be read at all.
+    //
+    // This is useful for excluding hopelessly unanalyzable
+    // files that can't be removed for whatever reason.
+    'exclude_file_list' => [
+        'vendor/composer/composer/src/Composer/InstalledVersions.php'
+    ],
+
+    // A directory list that defines files that will be excluded
+    // from static analysis, but whose class and method
+    // information should be included.
+    //
+    // Generally, you'll want to include the directories for
+    // third-party code (such as "vendor/") in this list.
+    //
+    // n.b.: If you'd like to parse but not analyze 3rd
+    //       party code, directories containing that code
+    //       should be added to the `directory_list` as well as
+    //       to `exclude_analysis_directory_list`.
+    'exclude_analysis_directory_list' => [
+        'vendor/',
+        'proto/',
+        'thrift/'
+    ],
+
+    // Enable this to enable checks of require/include statements referring to valid paths.
+    'enable_include_path_checks' => true,
+
+    // The number of processes to fork off during the analysis
+    // phase.
+    'processes' => 1,
+
+    // List of case-insensitive file extensions supported by Phan.
+    // (e.g. `['php', 'html', 'htm']`)
+    'analyzed_file_extensions' => [
+        'php',
+    ],
+
+    // You can put paths to stubs of internal extensions in this config option.
+    // If the corresponding extension is **not** loaded, then Phan will use the stubs instead.
+    // Phan will continue using its detailed type annotations,
+    // but load the constants, classes, functions, and classes (and their Reflection types)
+    // from these stub files (doubling as valid php files).
+    // Use a different extension from php to avoid accidentally loading these.
+    // The `tools/make_stubs` script can be used to generate your own stubs (compatible with php 7.0+ right now)
+    //
+    // (e.g. `['xdebug' => '.phan/internal_stubs/xdebug.phan_php']`)
+    'autoload_internal_extension_signatures' => [],
+
+    // A list of plugin files to execute.
+    //
+    // Plugins which are bundled with Phan can be added here by providing their name (e.g. `'AlwaysReturnPlugin'`)
+    //
+    // Documentation about available bundled plugins can be found [here](https://github.com/phan/phan/tree/master/.phan/plugins).
+    //
+    // Alternately, you can pass in the full path to a PHP file with the plugin's implementation (e.g. `'vendor/phan/phan/.phan/plugins/AlwaysReturnPlugin.php'`)
+    'plugins' => [
+        'AlwaysReturnPlugin',
+        'PregRegexCheckerPlugin',
+        'UnreachableCodePlugin',
+    ],
+
+    // A list of directories that should be parsed for class and
+    // method information. After excluding the directories
+    // defined in `exclude_analysis_directory_list`, the remaining
+    // files will be statically analyzed for errors.
+    //
+    // Thus, both first-party and third-party code being used by
+    // your application should be included in this list.
+    'directory_list' => [
+        'src',
+        'vendor'
+    ],
+
+    // A list of individual files to include in analysis
+    // with a path relative to the root directory of the
+    // project.
+    'file_list' => [],
+];
diff --git a/src/Instrumentation/ReactPHP/.php-cs-fixer.php b/src/Instrumentation/ReactPHP/.php-cs-fixer.php
new file mode 100644
index 000000000..e35fa078c
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/.php-cs-fixer.php
@@ -0,0 +1,43 @@
+<?php
+$finder = PhpCsFixer\Finder::create()
+    ->exclude('vendor')
+    ->exclude('var/cache')
+    ->in(__DIR__);
+
+$config = new PhpCsFixer\Config();
+return $config->setRules([
+    'concat_space' => ['spacing' => 'one'],
+    'declare_equal_normalize' => ['space' => 'none'],
+    'is_null' => true,
+    'modernize_types_casting' => true,
+    'ordered_imports' => true,
+    'php_unit_construct' => true,
+    'single_line_comment_style' => true,
+    'yoda_style' => false,
+    '@PSR2' => true,
+    'array_syntax' => ['syntax' => 'short'],
+    'blank_line_after_opening_tag' => true,
+    'blank_line_before_statement' => true,
+    'cast_spaces' => true,
+    'declare_strict_types' => true,
+    'type_declaration_spaces' => true,
+    'include' => true,
+    'lowercase_cast' => true,
+    'new_with_parentheses' => true,
+    'no_extra_blank_lines' => true,
+    'no_leading_import_slash' => true,
+    'echo_tag_syntax' => true,
+    'no_unused_imports' => true,
+    'no_useless_else' => true,
+    'no_useless_return' => true,
+    'phpdoc_order' => true,
+    'phpdoc_scalar' => true,
+    'phpdoc_types' => true,
+    'short_scalar_cast' => true,
+    'blank_lines_before_namespace' => true,
+    'single_quote' => true,
+    'trailing_comma_in_multiline' => true,
+    ])
+    ->setRiskyAllowed(true)
+    ->setFinder($finder);
+
diff --git a/src/Instrumentation/ReactPHP/README.md b/src/Instrumentation/ReactPHP/README.md
new file mode 100644
index 000000000..f621f646a
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/README.md
@@ -0,0 +1,43 @@
+[![Releases](https://img.shields.io/badge/releases-purple)](https://github.com/opentelemetry-php/contrib-auto-reactphp/releases)
+[![Issues](https://img.shields.io/badge/issues-pink)](https://github.com/open-telemetry/opentelemetry-php/issues)
+[![Source](https://img.shields.io/badge/source-contrib-green)](https://github.com/open-telemetry/opentelemetry-php-contrib/tree/main/src/Instrumentation/ReactPHP)
+[![Mirror](https://img.shields.io/badge/mirror-opentelemetry--php--contrib-blue)](https://github.com/opentelemetry-php/contrib-auto-reactphp)
+[![Latest Version](http://poser.pugx.org/open-telemetry/opentelemetry-auto-reactphp/v/unstable)](https://packagist.org/packages/open-telemetry/opentelemetry-auto-reactphp/)
+[![Stable](http://poser.pugx.org/open-telemetry/opentelemetry-auto-reactphp/v/stable)](https://packagist.org/packages/open-telemetry/opentelemetry-auto-reactphp/)
+
+This is a read-only subtree split of https://github.com/open-telemetry/opentelemetry-php-contrib.
+
+# OpenTelemetry ReactPHP HTTP Browser auto-instrumentation
+
+Please read https://opentelemetry.io/docs/instrumentation/php/automatic/ for instructions on how to
+install and configure the extension and SDK.
+
+## Overview
+
+Auto-instrumentation hooks are registered via composer, which will:
+
+* create spans automatically for each ReactPHP HTTP Browser request that is sent
+* add a `traceparent` header to the request to facilitate distributed tracing
+
+Note that span lifetime behavior differs based on how ReactPHP is utilized; see [examples/README.md](examples/README.md) for more information.
+
+## Configuration
+
+The extension can be disabled via [runtime configuration](https://opentelemetry.io/docs/instrumentation/php/sdk/#configuration):
+
+```shell
+OTEL_PHP_DISABLED_INSTRUMENTATIONS=reactphp
+```
+
+Custom HTTP methods can replace the known methods via environment variables, e.g.:
+
+```shell
+OTEL_INSTRUMENTATION_HTTP_KNOWN_METHODS="GET,HEAD,POST,PUT,DELETE,CONNECT,OPTIONS,TRACE,PATCH,MyCustomMethod"
+```
+
+Request and/or response headers can be added as span attributes via environment variables, e.g.:
+
+```shell
+OTEL_PHP_INSTRUMENTATION_HTTP_REQUEST_HEADERS=Accept
+OTEL_PHP_INSTRUMENTATION_HTTP_RESPONSE_HEADERS="Content-Length,Content-Type"
+```
diff --git a/src/Instrumentation/ReactPHP/_register.php b/src/Instrumentation/ReactPHP/_register.php
new file mode 100644
index 000000000..0900c4b23
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/_register.php
@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+use OpenTelemetry\Contrib\Instrumentation\ReactPHP\ReactPHPInstrumentation;
+use OpenTelemetry\SDK\Sdk;
+
+if (class_exists(Sdk::class) && Sdk::isInstrumentationDisabled(ReactPHPInstrumentation::NAME) === true) {
+    return;
+}
+
+if (extension_loaded('opentelemetry') === false) {
+    trigger_error('The opentelemetry extension must be loaded in order to autoload the OpenTelemetry ReactPHP HTTP auto-instrumentation', E_USER_WARNING);
+
+    return;
+}
+
+ReactPHPInstrumentation::register();
diff --git a/src/Instrumentation/ReactPHP/composer.json b/src/Instrumentation/ReactPHP/composer.json
new file mode 100644
index 000000000..cc261f08b
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/composer.json
@@ -0,0 +1,48 @@
+{
+  "name": "open-telemetry/opentelemetry-auto-reactphp",
+  "description": "OpenTelemetry auto-instrumentation for ReactPHP's HTTP Browser.",
+  "keywords": ["opentelemetry", "otel", "open-telemetry", "tracing", "reactphp", "async", "instrumentation"],
+  "type": "library",
+  "homepage": "https://opentelemetry.io/docs/php",
+  "readme": "./README.md",
+  "license": "Apache-2.0",
+  "minimum-stability": "dev",
+  "prefer-stable": true,
+  "require": {
+    "php": "^8.1",
+    "ext-opentelemetry": "*",
+    "guzzlehttp/psr7": "^2.7",
+    "open-telemetry/api": "^1.0",
+    "open-telemetry/sem-conv": "^1.32",
+    "react/http": "^1.11.0"
+  },
+  "require-dev": {
+    "friendsofphp/php-cs-fixer": "^3",
+    "phan/phan": "^5.0",
+    "phpstan/phpstan": "^1.1",
+    "phpstan/phpstan-phpunit": "^1.0",
+    "psalm/plugin-phpunit": "^0.19.2",
+    "open-telemetry/sdk": "^1.0",
+    "phpunit/phpunit": "^9.5",
+    "react/async": "^4.3.0",
+    "vimeo/psalm": "6.4.0"
+  },
+  "autoload": {
+    "psr-4": {
+      "OpenTelemetry\\Contrib\\Instrumentation\\ReactPHP\\": "src/"
+    },
+    "files": [
+      "_register.php"
+    ]
+  },
+  "autoload-dev": {
+    "psr-4": {
+      "OpenTelemetry\\Tests\\Instrumentation\\ReactPHP\\": "tests/"
+    }
+  },
+  "config": {
+    "allow-plugins": {
+      "php-http/discovery": false
+    }
+  }
+}
diff --git a/src/Instrumentation/ReactPHP/examples/README.md b/src/Instrumentation/ReactPHP/examples/README.md
new file mode 100644
index 000000000..96b355cb6
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/examples/README.md
@@ -0,0 +1,71 @@
+# OpenTelemetry ReactPHP HTTP Browser Examples
+
+These examples show a few different ways of using the [ReactPHP HTTP](https://reactphp.org/http/) Browser.
+
+### [http_requests.php](http_requests.php)
+
+This is a “pure” example using only the ReactPHP HTTP library and it’s dependencies.
+
+Here the spans end once the full HTTP response is received. Note that the root (parent) span ends as soon as the other spans have started.
+
+#### Example output:
+
+```
+{root span - 1.033s}
+{span for 400:Bad Request - 0.144s}
+[HTTP/1.1 400 Bad Request] http://postman-echo.com:443/get
+{span for /stream - 0.450s}
+[HTTP/1.1 200 OK] https://postman-echo.com/stream/33554432
+{span for /get - 0.604s}
+[HTTP/1.1 200 OK] https://postman-echo.com/get
+{span for /delay - 1.996s}
+[HTTP/1.1 200 OK] https://postman-echo.com/delay/1
+```
+
+### [http_streaming_requests.php](http_streaming_requests.php)
+
+This is still using only the ReactPHP HTTP library and it’s dependencies, and handles all responses as streaming responses.
+
+Here the spans end once the HTTP headers are received but potentially before the full message body is received. Like the previous example, the root (parent) span ends as soon as the other spans have started.
+
+#### Example output:
+
+```
+{root span - 0.022s}
+{span for /get - 0.212s}
+[HTTP/1.1 200 OK] https://postman-echo.com/get: headers received.
+[HTTP/1.1 200 OK] https://postman-echo.com/get: body received.
+{span for /stream - 0.351s}
+[HTTP/1.1 200 OK] https://postman-echo.com/stream/33554432: headers received.
+{span for 400:Bad Request - 0.081s}
+[HTTP/1.1 400 Bad Request] http://postman-echo.com:443/get
+[HTTP/1.1 200 OK] https://postman-echo.com/stream/33554432: body received.
+{span for /delay - 1.173s}
+[HTTP/1.1 200 OK] https://postman-echo.com/delay/1: headers received.
+[HTTP/1.1 200 OK] https://postman-echo.com/delay/1: body received.
+```
+
+### [http_requests_with_async.php](http_requests_with_async.php)
+
+This uses the [ReactPHP Async library](https://reactphp.org/async/) to make asynchronous HTTP requests while abstracting away the callables of Promises by taking advantage of PHP fibers.
+
+The responses are not handled as streaming, so as in the first example, the spans end once the full HTTP response is received. Unlike the previous two examples, the root (parent) span is “held open” until all child spans have ended.
+
+#### Example output:
+
+```
+Some other event loop event
+{span for /get - 0.189s}
+[HTTP/1.1 200 OK] https://postman-echo.com/get
+Some other event loop event
+{span for /stream - 1.685s}
+[HTTP/1.1 200 OK] https://postman-echo.com/stream/33554432
+{span for 400:Bad Request - 0.081s}
+[HTTP/1.1 400 Bad Request] http://postman-echo.com:443/get
+Some other event loop event
+Some other event loop event
+{span for /delay - 1.182s}
+[HTTP/1.1 200 OK] https://postman-echo.com/delay/1
+{root span - 4.169s}
+Some other event loop event
+```
diff --git a/src/Instrumentation/ReactPHP/examples/http_requests.php b/src/Instrumentation/ReactPHP/examples/http_requests.php
new file mode 100644
index 000000000..9d4af59b5
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/examples/http_requests.php
@@ -0,0 +1,87 @@
+<?php
+
+declare(strict_types=1);
+
+use OpenTelemetry\API\Trace\Propagation\TraceContextPropagator;
+use OpenTelemetry\SDK\Common\Export\Stream\StreamTransportFactory;
+use OpenTelemetry\SDK\Resource\ResourceInfoFactory;
+use OpenTelemetry\SDK\Sdk;
+use OpenTelemetry\SDK\Trace\Sampler\AlwaysOnSampler;
+use OpenTelemetry\SDK\Trace\SpanExporter\ConsoleSpanExporter;
+use OpenTelemetry\SDK\Trace\SpanProcessor\SimpleSpanProcessor;
+use OpenTelemetry\SDK\Trace\TracerProvider;
+use Psr\Http\Message\ResponseInterface;
+use React\Http\Browser;
+use React\Http\Message\Request;
+use React\Http\Message\ResponseException;
+
+require_once dirname(__DIR__) . '/vendor/autoload.php';
+
+$transport = (new StreamTransportFactory())->create('php://output', 'application/json');
+$exporter = new ConsoleSpanExporter($transport);
+
+$tracerProvider =  new TracerProvider(
+    new SimpleSpanProcessor($exporter),
+    new AlwaysOnSampler(),
+    ResourceInfoFactory::emptyResource(),
+);
+
+Sdk::builder()
+    ->setTracerProvider($tracerProvider)
+    ->setPropagator(TraceContextPropagator::getInstance())
+    ->setAutoShutdown(true)
+    ->buildAndRegisterGlobal();
+
+$root = $tracerProvider->getTracer('reactphp-demo')->spanBuilder('root')->startSpan();
+$rootScope = $root->activate();
+
+try {
+    $browser = new Browser();
+
+    $requests = [
+        new Request('GET', 'https://postman-echo.com/get'),
+        new Request('GET', 'https://postman-echo.com/stream/33554432'),
+        new Request('POST', 'https://postman-echo.com/post', ['Content-Type' => 'application/json'], '{}'),
+        new Request('CUSTOM', 'http://postman-echo.com:443/get'),
+        new Request('GET', 'unknown://postman-echo.com/get'),
+        new Request('GET', 'https://postman-echo.com/delay/2'),
+    ];
+
+    foreach ($requests as $request) {
+        $browser
+            ->request($request->getMethod(), $request->getUri())
+            ->then(function (ResponseInterface $response) use ($request) {
+                echo sprintf(
+                    '[HTTP/%s %d %s] %s%s',
+                    $response->getProtocolVersion(),
+                    $response->getStatusCode(),
+                    $response->getReasonPhrase(),
+                    $request->getUri(),
+                    PHP_EOL
+                );
+            }, function (Throwable $t) use ($request) {
+                if (is_a($t, ResponseException::class)) {
+                    $response = $t->getResponse();
+                    echo sprintf(
+                        '[HTTP/%s %d %s] %s%s',
+                        $response->getProtocolVersion(),
+                        $response->getStatusCode(),
+                        $response->getReasonPhrase(),
+                        $request->getUri(),
+                        PHP_EOL
+                    );
+                } else {
+                    echo sprintf(
+                        '[%d: %s] %s%s',
+                        $t->getCode(),
+                        $t->getMessage(),
+                        $request->getUri(),
+                        PHP_EOL
+                    );
+                }
+            });
+    }
+} finally {
+    $rootScope->detach();
+    $root->end();
+}
diff --git a/src/Instrumentation/ReactPHP/examples/http_requests_with_async.php b/src/Instrumentation/ReactPHP/examples/http_requests_with_async.php
new file mode 100644
index 000000000..e1f2ab86a
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/examples/http_requests_with_async.php
@@ -0,0 +1,101 @@
+<?php
+
+declare(strict_types=1);
+
+use OpenTelemetry\API\Trace\Propagation\TraceContextPropagator;
+use OpenTelemetry\Context\Context;
+use OpenTelemetry\SDK\Common\Export\Stream\StreamTransportFactory;
+use OpenTelemetry\SDK\Resource\ResourceInfoFactory;
+use OpenTelemetry\SDK\Sdk;
+use OpenTelemetry\SDK\Trace\Sampler\AlwaysOnSampler;
+use OpenTelemetry\SDK\Trace\SpanExporter\ConsoleSpanExporter;
+use OpenTelemetry\SDK\Trace\SpanProcessor\SimpleSpanProcessor;
+use OpenTelemetry\SDK\Trace\TracerProvider;
+use function React\Async\async;
+use function React\Async\await;
+use React\EventLoop\Loop;
+use React\Http\Browser;
+use React\Http\Message\Request;
+use React\Http\Message\ResponseException;
+
+require_once dirname(__DIR__) . '/vendor/autoload.php';
+
+$transport = (new StreamTransportFactory())->create('php://output', 'application/json');
+$exporter = new ConsoleSpanExporter($transport);
+
+$tracerProvider = new TracerProvider(
+    new SimpleSpanProcessor($exporter),
+    new AlwaysOnSampler(),
+    ResourceInfoFactory::emptyResource(),
+);
+
+Sdk::builder()
+    ->setTracerProvider($tracerProvider)
+    ->setPropagator(TraceContextPropagator::getInstance())
+    ->setAutoShutdown(true)
+    ->buildAndRegisterGlobal();
+
+$context = Context::getCurrent();
+
+$root = $tracerProvider->getTracer('reactphp-demo')->spanBuilder('root')->startSpan();
+
+$timer = Loop::addPeriodicTimer(1, function () {
+    echo 'Some other event loop event' . PHP_EOL;
+});
+
+Loop::futureTick(async(static function () use ($context, $root, $timer) {
+    $contextScope = $context->activate();
+    $rootScope = $root->activate();
+
+    try {
+        sleep(1);
+
+        $browser = new Browser();
+
+        $requests = [
+            new Request('GET', 'https://postman-echo.com/get'),
+            new Request('GET', 'https://postman-echo.com/stream/33554432'),
+            new Request('POST', 'https://postman-echo.com/post', ['Content-Type' => 'application/json'], '{}'),
+            new Request('CUSTOM', 'http://postman-echo.com:443/get'),
+            new Request('GET', 'unknown://postman-echo.com/get'),
+            new Request('GET', 'https://postman-echo.com/delay/2'),
+        ];
+
+        foreach ($requests as $request) {
+            try {
+                $response = await($browser->request($request->getMethod(), $request->getUri()));
+                echo sprintf(
+                    '[HTTP/%s %d %s] %s%s',
+                    $response->getProtocolVersion(),
+                    $response->getStatusCode(),
+                    $response->getReasonPhrase(),
+                    $request->getUri(),
+                    PHP_EOL
+                );
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
+                echo sprintf(
+                    '[HTTP/%s %d %s] %s%s',
+                    $response->getProtocolVersion(),
+                    $response->getStatusCode(),
+                    $response->getReasonPhrase(),
+                    $request->getUri(),
+                    PHP_EOL
+                );
+            } catch (Throwable $t) {
+                echo sprintf(
+                    '[%d: %s] %s%s',
+                    $t->getCode(),
+                    $t->getMessage(),
+                    $request->getUri(),
+                    PHP_EOL
+                );
+            }
+        }
+    } finally {
+        $rootScope->detach();
+        $root->end();
+        $contextScope->detach();
+        Loop::cancelTimer($timer);
+    }
+}));
diff --git a/src/Instrumentation/ReactPHP/examples/http_streaming_requests.php b/src/Instrumentation/ReactPHP/examples/http_streaming_requests.php
new file mode 100644
index 000000000..57ffa01ba
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/examples/http_streaming_requests.php
@@ -0,0 +1,107 @@
+<?php
+
+declare(strict_types=1);
+
+use OpenTelemetry\API\Trace\Propagation\TraceContextPropagator;
+use OpenTelemetry\SDK\Common\Export\Stream\StreamTransportFactory;
+use OpenTelemetry\SDK\Resource\ResourceInfoFactory;
+use OpenTelemetry\SDK\Sdk;
+use OpenTelemetry\SDK\Trace\Sampler\AlwaysOnSampler;
+use OpenTelemetry\SDK\Trace\SpanExporter\ConsoleSpanExporter;
+use OpenTelemetry\SDK\Trace\SpanProcessor\SimpleSpanProcessor;
+use OpenTelemetry\SDK\Trace\TracerProvider;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\StreamInterface;
+use React\Http\Browser;
+use React\Http\Message\Request;
+use React\Http\Message\ResponseException;
+use React\Stream\ReadableStreamInterface;
+
+require_once dirname(__DIR__) . '/vendor/autoload.php';
+
+$transport = (new StreamTransportFactory())->create('php://output', 'application/json');
+$exporter = new ConsoleSpanExporter($transport);
+
+$tracerProvider =  new TracerProvider(
+    new SimpleSpanProcessor($exporter),
+    new AlwaysOnSampler(),
+    ResourceInfoFactory::emptyResource(),
+);
+
+Sdk::builder()
+    ->setTracerProvider($tracerProvider)
+    ->setPropagator(TraceContextPropagator::getInstance())
+    ->setAutoShutdown(true)
+    ->buildAndRegisterGlobal();
+
+$root = $tracerProvider->getTracer('reactphp-demo')->spanBuilder('root')->startSpan();
+$rootScope = $root->activate();
+
+try {
+    $browser = new Browser();
+
+    $requests = [
+        new Request('GET', 'https://postman-echo.com/get'),
+        new Request('GET', 'https://postman-echo.com/stream/33554432'),
+        new Request('POST', 'https://postman-echo.com/post', ['Content-Type' => 'application/json'], '{}'),
+        new Request('CUSTOM', 'http://postman-echo.com:443/get'),
+        new Request('GET', 'unknown://postman-echo.com/get'),
+        new Request('GET', 'https://postman-echo.com/delay/2'),
+    ];
+
+    foreach ($requests as $request) {
+        $browser
+            ->requestStreaming($request->getMethod(), $request->getUri())
+            ->then(function (ResponseInterface $response) use ($request) {
+                $prefix = sprintf(
+                    '[HTTP/%s %d %s] %s: ',
+                    $response->getProtocolVersion(),
+                    $response->getStatusCode(),
+                    $response->getReasonPhrase(),
+                    $request->getUri()
+                );
+                echo $prefix . 'headers received.' . PHP_EOL;
+
+                $stream = $response->getBody();
+                assert($stream instanceof StreamInterface);
+                assert($stream instanceof ReadableStreamInterface);
+
+                $stream->on('error', function (Throwable $t) use ($request) {
+                    echo sprintf(
+                        '[%d: %s] %s%s',
+                        $t->getCode(),
+                        $t->getMessage(),
+                        $request->getUri(),
+                        PHP_EOL
+                    );
+                });
+
+                $stream->on('close', function () use ($prefix) {
+                    echo $prefix . 'body received.' . PHP_EOL;
+                });
+            }, function (Throwable $t) use ($request) {
+                if (is_a($t, ResponseException::class)) {
+                    $response = $t->getResponse();
+                    echo sprintf(
+                        '[HTTP/%s %d %s] %s%s',
+                        $response->getProtocolVersion(),
+                        $response->getStatusCode(),
+                        $response->getReasonPhrase(),
+                        $request->getUri(),
+                        PHP_EOL
+                    );
+                } else {
+                    echo sprintf(
+                        '[%d: %s] %s%s',
+                        $t->getCode(),
+                        $t->getMessage(),
+                        $request->getUri(),
+                        PHP_EOL
+                    );
+                }
+            });
+    }
+} finally {
+    $rootScope->detach();
+    $root->end();
+}
diff --git a/src/Instrumentation/ReactPHP/phpstan.neon.dist b/src/Instrumentation/ReactPHP/phpstan.neon.dist
new file mode 100644
index 000000000..ed94c13da
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/phpstan.neon.dist
@@ -0,0 +1,9 @@
+includes:
+    - vendor/phpstan/phpstan-phpunit/extension.neon
+
+parameters:
+    tmpDir: var/cache/phpstan
+    level: 5
+    paths:
+        - src
+        - tests
diff --git a/src/Instrumentation/ReactPHP/phpunit.xml.dist b/src/Instrumentation/ReactPHP/phpunit.xml.dist
new file mode 100644
index 000000000..50fd90fa8
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/phpunit.xml.dist
@@ -0,0 +1,50 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<phpunit
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.5/phpunit.xsd"
+    backupGlobals="false"
+    backupStaticAttributes="false"
+    cacheResult="false"
+    colors="false"
+    convertErrorsToExceptions="true"
+    convertNoticesToExceptions="true"
+    convertWarningsToExceptions="true"
+    forceCoversAnnotation="false"
+    processIsolation="false"
+    stopOnError="false"
+    stopOnFailure="false"
+    stopOnIncomplete="false"
+    stopOnSkipped="false"
+    stopOnRisky="false"
+    timeoutForSmallTests="1"
+    timeoutForMediumTests="10"
+    timeoutForLargeTests="60"
+    verbose="true">
+
+    <coverage processUncoveredFiles="true" disableCodeCoverageIgnore="false">
+        <include>
+            <directory>src</directory>
+        </include>
+    </coverage>
+
+    <php>
+        <env name="OTEL_INSTRUMENTATION_HTTP_KNOWN_METHODS" value="GET,HEAD,POST,PUT,DELETE,CONNECT,OPTIONS,TRACE,PATCH,CUSTOM" />
+        <env name="OTEL_PHP_INSTRUMENTATION_HTTP_REQUEST_HEADERS" value="traceparent" />
+        <env name="OTEL_PHP_INSTRUMENTATION_HTTP_RESPONSE_HEADERS" value="Content-Type" />
+        <ini name="date.timezone" value="UTC" />
+        <ini name="display_errors" value="On" />
+        <ini name="display_startup_errors" value="On" />
+        <ini name="error_reporting" value="E_ALL" />
+    </php>
+
+    <testsuites>
+        <testsuite name="unit">
+            <directory>tests/Unit</directory>
+        </testsuite>
+        <testsuite name="integration">
+            <directory>tests/Integration</directory>
+        </testsuite>
+    </testsuites>
+
+</phpunit>
diff --git a/src/Instrumentation/ReactPHP/psalm.xml.dist b/src/Instrumentation/ReactPHP/psalm.xml.dist
new file mode 100644
index 000000000..155711712
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/psalm.xml.dist
@@ -0,0 +1,15 @@
+<?xml version="1.0"?>
+<psalm
+    errorLevel="3"
+    cacheDirectory="var/cache/psalm"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="https://getpsalm.org/schema/config"
+    xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd">
+    <projectFiles>
+        <directory name="src"/>
+        <directory name="tests"/>
+    </projectFiles>
+    <plugins>
+        <pluginClass class="Psalm\PhpUnitPlugin\Plugin"/>
+    </plugins>
+</psalm>
diff --git a/src/Instrumentation/ReactPHP/src/HeadersPropagator.php b/src/Instrumentation/ReactPHP/src/HeadersPropagator.php
new file mode 100644
index 000000000..d03458e27
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/src/HeadersPropagator.php
@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\Contrib\Instrumentation\ReactPHP;
+
+use function assert;
+use OpenTelemetry\Context\Propagation\PropagationSetterInterface;
+use Psr\Http\Message\RequestInterface;
+
+/**
+ * @internal
+ */
+class HeadersPropagator implements PropagationSetterInterface
+{
+    public static function instance(): self
+    {
+        static $instance;
+
+        return $instance ??= new self();
+    }
+
+    /** @param RequestInterface $carrier */
+    public function set(&$carrier, string $key, string $value): void
+    {
+        assert($carrier instanceof RequestInterface);
+
+        $carrier = $carrier->withAddedHeader($key, $value);
+    }
+}
diff --git a/src/Instrumentation/ReactPHP/src/ReactPHPInstrumentation.php b/src/Instrumentation/ReactPHP/src/ReactPHPInstrumentation.php
new file mode 100644
index 000000000..8e20a0dcb
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/src/ReactPHPInstrumentation.php
@@ -0,0 +1,281 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\Contrib\Instrumentation\ReactPHP;
+
+use Composer\InstalledVersions;
+use GuzzleHttp\Psr7\Query;
+use OpenTelemetry\API\Globals;
+use OpenTelemetry\API\Instrumentation\CachedInstrumentation;
+use OpenTelemetry\API\Trace\Span;
+use OpenTelemetry\API\Trace\SpanKind;
+use OpenTelemetry\API\Trace\StatusCode;
+use OpenTelemetry\Context\Context;
+use function OpenTelemetry\Instrumentation\hook;
+use OpenTelemetry\SemConv\TraceAttributes;
+use OpenTelemetry\SemConv\TraceAttributeValues;
+use OpenTelemetry\SemConv\Version;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\UriInterface;
+use React\Http\Io\Transaction;
+use React\Http\Message\ResponseException;
+use React\Promise\PromiseInterface;
+use Throwable;
+
+/** @psalm-suppress UnusedClass */
+class ReactPHPInstrumentation
+{
+    public const NAME = 'reactphp';
+    /**
+     * The name of the Composer package.
+     *
+     * @see https://getcomposer.org/doc/04-schema.md#name
+     */
+    private const COMPOSER_NAME = 'open-telemetry/opentelemetry-auto-reactphp';
+    /**
+     * The environment variable which overrides the default list of known HTTP methods.
+     * This supports a comma-separated list of case-sensitive known HTTP methods.
+     *
+     * @see https://opentelemetry.io/docs/specs/semconv/attributes-registry/http/#http-request-method
+     */
+    private const ENV_HTTP_KNOWN_METHODS = 'OTEL_INSTRUMENTATION_HTTP_KNOWN_METHODS';
+    /**
+     * The environment variable which configures the request headers to be captured (default is none).
+     * This supports a comma-separated list of case-insensitive HTTP header keys.
+     *
+     * @see https://opentelemetry.io/docs/specs/semconv/http/http-spans/#http-client-span
+     */
+    private const ENV_HTTP_REQUEST_HEADERS = 'OTEL_PHP_INSTRUMENTATION_HTTP_REQUEST_HEADERS';
+    /**
+     * The environment variable which configures the response headers to be captured (default is none).
+     * This supports a comma-separated list of case-insensitive HTTP header keys.
+     *
+     * @see https://opentelemetry.io/docs/specs/semconv/http/http-spans/#http-client-span
+     */
+    private const ENV_HTTP_RESPONSE_HEADERS = 'OTEL_PHP_INSTRUMENTATION_HTTP_RESPONSE_HEADERS';
+    /**
+     * The `{method}` component of the span name when the original method is not known to the instrumentation.
+     *
+     * @see https://opentelemetry.io/docs/specs/semconv/http/http-spans/#name
+     */
+    private const HTTP_REQUEST_METHOD_HTTP = 'HTTP';
+    /**
+     * Name of this instrumentation library which provides the instrumentation for ReactPHP.
+     *
+     * @see https://opentelemetry.io/docs/specs/otel/glossary/#instrumentation-library
+     */
+    private const INSTRUMENTATION_LIBRARY_NAME = 'io.opentelemetry.contrib.php.reactphp';
+    /**
+     * Query string keys to be redacted by default.
+     *
+     * @see https://opentelemetry.io/docs/specs/semconv/attributes-registry/url/#url-query
+     */
+    private const URL_QUERY_REDACT_KEYS = ['AWSAccessKeyId', 'Signature', 'sig', 'X-Goog-Signature'];
+    /**
+     * Value used to replace any sensitive content in the URL.
+     *
+     * @see https://opentelemetry.io/docs/specs/semconv/attributes-registry/url/#url-full
+     */
+    private const URL_REDACTION = 'REDACTED';
+
+    public static function register(): void
+    {
+        $instrumentation = new CachedInstrumentation(
+            self::INSTRUMENTATION_LIBRARY_NAME,
+            InstalledVersions::getPrettyVersion(self::COMPOSER_NAME),
+            Version::VERSION_1_32_0->url()
+        );
+
+        /** @psalm-suppress UnusedFunctionCall */
+        hook(
+            Transaction::class,
+            'send',
+            pre: static function (Transaction $transaction, array $params, string $class, string $function, ?string $filename, ?int $lineno) use ($instrumentation): array {
+                /** @var \Psr\Http\Message\RequestInterface */
+                $request = $params[0];
+
+                $propagator = Globals::propagator();
+                $parentContext = Context::getCurrent();
+
+                foreach ($propagator->fields() as $field) {
+                    $request = $request->withoutHeader($field);
+                }
+
+                /** @var non-empty-string|null */
+                $method = self::canonizeMethod($request->getMethod());
+
+                $spanBuilder = $instrumentation
+                    ->tracer()
+                    // https://opentelemetry.io/docs/specs/semconv/http/http-spans/#http-client-span
+                    ->spanBuilder($method ?? self::HTTP_REQUEST_METHOD_HTTP)
+                    ->setParent($parentContext)
+                    ->setSpanKind(SpanKind::KIND_CLIENT)
+                    ->setAttribute(TraceAttributes::HTTP_REQUEST_METHOD, $method ?? TraceAttributeValues::HTTP_REQUEST_METHOD_OTHER)
+                    ->setAttribute(TraceAttributes::SERVER_ADDRESS, $request->getUri()->getHost())
+                    ->setAttribute(TraceAttributes::SERVER_PORT, $request->getUri()->getPort() ?? ($request->getUri()->getScheme() === 'https' ? 443 : 80))
+                    ->setAttribute(TraceAttributes::URL_FULL, self::sanitizeUrl($request->getUri()))
+                    // https://opentelemetry.io/docs/specs/semconv/code/
+                    ->setAttribute(TraceAttributes::CODE_FUNCTION_NAME, sprintf('%s::%s', $class, $function));
+
+                // https://opentelemetry.io/docs/specs/semconv/http/http-spans/#http-client-span
+                if ($method === null) {
+                    $spanBuilder->setAttribute(TraceAttributes::HTTP_REQUEST_METHOD_ORIGINAL, $request->getMethod());
+                }
+
+                // https://opentelemetry.io/docs/specs/semconv/code/
+                /** @psalm-suppress RiskyTruthyFalsyComparison */
+                if ($filename) {
+                    $spanBuilder->setAttribute(TraceAttributes::CODE_FILE_PATH, $filename);
+                }
+                /** @psalm-suppress RiskyTruthyFalsyComparison */
+                if ($lineno) {
+                    $spanBuilder->setAttribute(TraceAttributes::CODE_LINE_NUMBER, $lineno);
+                }
+
+                $span = $spanBuilder->startSpan();
+                $context = $span->storeInContext($parentContext);
+                $propagator->inject($request, HeadersPropagator::instance(), $context);
+
+                foreach (explode(',', $_ENV[self::ENV_HTTP_REQUEST_HEADERS] ?? '') as $header) {
+                    if ($request->hasHeader($header)) {
+                        $span->setAttribute(
+                            sprintf('%s.%s', TraceAttributes::HTTP_REQUEST_HEADER, strtolower($header)),
+                            $request->getHeader($header)
+                        );
+                    }
+                }
+
+                Context::storage()->attach($context);
+
+                return [$request];
+            },
+            post: static function (Transaction $transaction, array $params, PromiseInterface $promise): PromiseInterface {
+                $scope = Context::storage()->scope();
+                $scope?->detach();
+
+                if (!$scope) {
+                    return $promise;
+                }
+
+                $span = Span::fromContext($scope->context());
+
+                if (!$span->isRecording()) {
+                    return $promise;
+                }
+
+                return $promise->then(
+                    onFulfilled: function (ResponseInterface $response) use ($span) {
+                        // https://opentelemetry.io/docs/specs/semconv/http/http-spans/#http-client-span
+                        $span
+                            ->setAttribute(TraceAttributes::HTTP_RESPONSE_STATUS_CODE, $response->getStatusCode())
+                            ->setAttribute(TraceAttributes::NETWORK_PROTOCOL_VERSION, $response->getProtocolVersion());
+
+                        if ($response->getStatusCode() >= 400 && $response->getStatusCode() < 600) {
+                            $span
+                                ->setStatus(StatusCode::STATUS_ERROR)
+                                ->setAttribute(TraceAttributes::ERROR_TYPE, (string) $response->getStatusCode());
+                        }
+
+                        foreach (explode(',', $_ENV[self::ENV_HTTP_RESPONSE_HEADERS] ?? '') as $header) {
+                            if ($response->hasHeader($header)) {
+                                $span->setAttribute(
+                                    sprintf('%s.%s', TraceAttributes::HTTP_RESPONSE_HEADER, strtolower($header)),
+                                    $response->getHeader($header)
+                                );
+                            }
+                        }
+
+                        $span->end();
+
+                        return $response;
+                    },
+                    onRejected: function (Throwable $t) use ($span) {
+                        $span->recordException($t);
+                        if (is_a($t, ResponseException::class)) {
+                            // https://opentelemetry.io/docs/specs/semconv/http/http-spans/#http-client-span
+                            $span
+                                ->setStatus(StatusCode::STATUS_ERROR)
+                                ->setAttribute(TraceAttributes::ERROR_TYPE, (string) $t->getCode())
+                                ->setAttribute(TraceAttributes::HTTP_RESPONSE_STATUS_CODE, $t->getCode())
+                                ->setAttribute(TraceAttributes::NETWORK_PROTOCOL_VERSION, $t->getResponse()->getProtocolVersion());
+
+                            foreach (explode(',', $_ENV[self::ENV_HTTP_RESPONSE_HEADERS] ?? '') as $header) {
+                                if ($t->getResponse()->hasHeader($header)) {
+                                    $span->setAttribute(
+                                        sprintf('%s.%s', TraceAttributes::HTTP_RESPONSE_HEADER, strtolower($header)),
+                                        $t->getResponse()->getHeader($header)
+                                    );
+                                }
+                            }
+                        } else {
+                            $span
+                                ->setStatus(StatusCode::STATUS_ERROR, $t->getMessage())
+                                ->setAttribute(TraceAttributes::ERROR_TYPE, $t::class);
+                        }
+
+                        $span->end();
+
+                        throw $t;
+                    }
+                );
+            }
+        );
+    }
+
+    private static function canonizeMethod(string $method): ?string
+    {
+        // RFC9110, RFC5789
+        $knownMethods = [
+            TraceAttributeValues::HTTP_REQUEST_METHOD_GET,
+            TraceAttributeValues::HTTP_REQUEST_METHOD_HEAD,
+            TraceAttributeValues::HTTP_REQUEST_METHOD_POST,
+            TraceAttributeValues::HTTP_REQUEST_METHOD_PUT,
+            TraceAttributeValues::HTTP_REQUEST_METHOD_DELETE,
+            TraceAttributeValues::HTTP_REQUEST_METHOD_CONNECT,
+            TraceAttributeValues::HTTP_REQUEST_METHOD_OPTIONS,
+            TraceAttributeValues::HTTP_REQUEST_METHOD_TRACE,
+            TraceAttributeValues::HTTP_REQUEST_METHOD_PATCH,
+        ];
+
+        $overrideMethods = $_ENV[self::ENV_HTTP_KNOWN_METHODS] ?? '';
+        if (!empty($overrideMethods)) {
+            $knownMethods = explode(',', $overrideMethods);
+        }
+
+        if (in_array($method, $knownMethods)) {
+            return $method;
+        }
+
+        return null;
+    }
+
+    private static function sanitizeUrl(UriInterface $uri): string
+    {
+        $userInfo = $uri->getUserInfo();
+        if (str_contains($userInfo, ':')) {
+            $uri = $uri->withUserInfo(self::URL_REDACTION, self::URL_REDACTION);
+        } elseif ($userInfo !== '') {
+            $uri = $uri->withUserInfo(self::URL_REDACTION);
+        }
+
+        $queryString = $uri->getQuery();
+        // http_build_query(parse_str()) is not idempotent, so using Guzzle’s Query class for now
+        if ($queryString !== '') {
+            $queryParameters = Query::parse($queryString);
+            $queryParameters = array_merge(
+                $queryParameters,
+                array_intersect_key(
+                    array_fill_keys(
+                        self::URL_QUERY_REDACT_KEYS,
+                        self::URL_REDACTION
+                    ),
+                    $queryParameters
+                )
+            );
+            $uri = $uri->withQuery(Query::build($queryParameters));
+        }
+
+        return (string) $uri;
+    }
+}
diff --git a/src/Instrumentation/ReactPHP/tests/Integration/ReactPHPInstrumentationTest.php b/src/Instrumentation/ReactPHP/tests/Integration/ReactPHPInstrumentationTest.php
new file mode 100644
index 000000000..586bb861c
--- /dev/null
+++ b/src/Instrumentation/ReactPHP/tests/Integration/ReactPHPInstrumentationTest.php
@@ -0,0 +1,202 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenTelemetry\Instrumentation\ReactPHP\tests\Integration;
+
+use ArrayObject;
+use OpenTelemetry\API\Instrumentation\Configurator;
+use OpenTelemetry\API\Trace\Propagation\TraceContextPropagator;
+use OpenTelemetry\API\Trace\StatusCode;
+use OpenTelemetry\Context\ScopeInterface;
+use OpenTelemetry\Contrib\Instrumentation\ReactPHP\ReactPHPInstrumentation;
+use OpenTelemetry\SDK\Trace\ImmutableSpan;
+use OpenTelemetry\SDK\Trace\SpanExporter\InMemoryExporter;
+use OpenTelemetry\SDK\Trace\SpanProcessor\SimpleSpanProcessor;
+use OpenTelemetry\SDK\Trace\TracerProvider;
+use OpenTelemetry\SemConv\TraceAttributes;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+use Psr\Http\Message\RequestInterface;
+use React\EventLoop\LoopInterface;
+use React\Http\Browser;
+use React\Http\Io\Sender;
+use React\Http\Io\Transaction;
+use React\Http\Message\Response;
+use React\Http\Message\ResponseException;
+use function React\Promise\reject;
+use function React\Promise\resolve;
+
+class ReactPHPInstrumentationTest extends TestCase
+{
+    private Browser $browser;
+
+    private ArrayObject $storage;
+    private TracerProvider $tracerProvider;
+    private ScopeInterface $scope;
+
+    public function setUp(): void
+    {
+        /**
+         * Browser/Transaction set up, pulled from ReactPHP tests:
+         * @see https://github.com/reactphp/http/blob/1.x/tests/BrowserTest.php
+         * @see https://github.com/reactphp/http/blob/1.x/tests/Io/TransactionTest.php
+         *
+         * @var LoopInterface&MockObject
+         */
+        $loop = $this->createMock(LoopInterface::class);
+        /** @var Sender&MockObject */
+        $sender = $this->createMock(Sender::class);
+        $sender->method('send')
+            ->willReturnCallback(function (RequestInterface $request) {
+                /** @psalm-suppress InternalMethod */
+                return match ($request->getUri()->getPath()) {
+                    '/network_error' => resolve(
+                        (new Response())
+                            ->withStatus(400)
+                            ->withAddedHeader('Content-Type', 'text/plain; charset=utf-8')
+                    ),
+                    '/unknown_error' => reject(new \Exception('Unknown')),
+                    default => resolve(Response::plaintext('Hello world'))
+                };
+            });
+        /** @psalm-suppress InternalClass,InternalMethod */
+        $transaction = new Transaction($sender, $loop);
+        $this->browser = new Browser(null, $loop);
+        $ref = new \ReflectionProperty($this->browser, 'transaction');
+        $ref->setValue($this->browser, $transaction);
+
+        /**
+         * OpenTelemetry set up
+         */
+        $this->storage = new ArrayObject();
+        $this->tracerProvider = new TracerProvider(
+            new SimpleSpanProcessor(
+                new InMemoryExporter($this->storage)
+            )
+        );
+
+        $this->scope = Configurator::create()
+            ->withTracerProvider($this->tracerProvider)
+            ->withPropagator(TraceContextPropagator::getInstance())
+            ->activate();
+    }
+
+    public function tearDown(): void
+    {
+        $this->scope->detach();
+        $this->tracerProvider->shutdown();
+    }
+
+    public function test_fulfilled_promise(): void
+    {
+        $this->assertCount(0, $this->storage);
+
+        $this->browser->request('GET', 'http://example.com/success?query#fragment')->then();
+
+        $this->assertCount(1, $this->storage);
+
+        $span = $this->storage->offsetGet(0);
+        assert($span instanceof ImmutableSpan);
+        $this->assertSame('GET', $span->getName());
+        $this->assertSame('GET', $span->getAttributes()->get(TraceAttributes::HTTP_REQUEST_METHOD));
+        $this->assertSame('example.com', $span->getAttributes()->get(TraceAttributes::SERVER_ADDRESS));
+        $this->assertSame('http://example.com/success?query#fragment', $span->getAttributes()->get(TraceAttributes::URL_FULL));
+        $this->assertSame('React\Http\Io\Transaction::send', $span->getAttributes()->get(TraceAttributes::CODE_FUNCTION_NAME));
+        $this->assertSame(80, $span->getAttributes()->get(TraceAttributes::SERVER_PORT));
+        $this->assertNotEmpty($span->getAttributes()->get(sprintf('%s.%s', TraceAttributes::HTTP_REQUEST_HEADER, 'traceparent')));
+        $this->assertStringEndsWith('vendor/react/http/src/Io/Transaction.php', $span->getAttributes()->get(TraceAttributes::CODE_FILE_PATH));
+        $this->assertSame(200, $span->getAttributes()->get(TraceAttributes::HTTP_RESPONSE_STATUS_CODE));
+        $this->assertSame('1.1', $span->getAttributes()->get(TraceAttributes::NETWORK_PROTOCOL_VERSION));
+        $this->assertSame(['text/plain; charset=utf-8'], $span->getAttributes()->get(sprintf('%s.%s', TraceAttributes::HTTP_RESPONSE_HEADER, 'content-type')));
+    }
+
+    public function test_fulfilled_promise_with_redactions(): void
+    {
+        $this->browser->request('GET', 'http://username@example.com/success')->then();
+
+        $span = $this->storage->offsetGet(0);
+        $this->assertSame('http://REDACTED@example.com/success', $span->getAttributes()->get(TraceAttributes::URL_FULL));
+
+        $this->browser->request('GET', 'http://username:password@example.com/success?Signature=private')->then();
+
+        $span = $this->storage->offsetGet(1);
+        $this->assertSame('http://REDACTED:REDACTED@example.com/success?Signature=REDACTED', $span->getAttributes()->get(TraceAttributes::URL_FULL));
+    }
+
+    public function test_fulfilled_promise_with_overridden_methods(): void
+    {
+        $this->browser->request('CUSTOM', 'http://example.com:8888/success')->then();
+
+        $span = $this->storage->offsetGet(0);
+        $this->assertSame('CUSTOM', $span->getName());
+        $this->assertSame('CUSTOM', $span->getAttributes()->get(TraceAttributes::HTTP_REQUEST_METHOD));
+        $this->assertSame(8888, $span->getAttributes()->get(TraceAttributes::SERVER_PORT));
+        $this->assertNull($span->getAttributes()->get(TraceAttributes::HTTP_REQUEST_METHOD_ORIGINAL));
+    }
+
+    public function test_fulfilled_promise_with_unknown_method(): void
+    {
+        $this->browser->request('UNKNOWN', 'http://example.com/success')->then();
+
+        $span = $this->storage->offsetGet(0);
+        $this->assertSame('HTTP', $span->getName());
+        $this->assertSame('_OTHER', $span->getAttributes()->get(TraceAttributes::HTTP_REQUEST_METHOD));
+        $this->assertSame('UNKNOWN', $span->getAttributes()->get(TraceAttributes::HTTP_REQUEST_METHOD_ORIGINAL));
+    }
+
+    public function test_fulfilled_promise_with_error(): void
+    {
+        $browser = $this->browser->withRejectErrorResponse(false);
+        $browser->request('GET', 'http://example.com/network_error')->then();
+
+        $span = $this->storage->offsetGet(0);
+        $this->assertSame(StatusCode::STATUS_ERROR, $span->getStatus()->getCode());
+        $this->assertSame('400', $span->getAttributes()->get(TraceAttributes::ERROR_TYPE));
+        $this->assertSame(400, $span->getAttributes()->get(TraceAttributes::HTTP_RESPONSE_STATUS_CODE));
+    }
+
+    public function test_rejected_promise_with_response_exception(): void
+    {
+        $this->browser->request('GET', 'http://example.com/network_error')->then(null, function () {});
+
+        $span = $this->storage->offsetGet(0);
+        $this->assertSame(StatusCode::STATUS_ERROR, $span->getStatus()->getCode());
+        $this->assertSame('400', $span->getAttributes()->get(TraceAttributes::ERROR_TYPE));
+        $this->assertSame(400, $span->getAttributes()->get(TraceAttributes::HTTP_RESPONSE_STATUS_CODE));
+        $event = $span->getEvents()[0];
+        $this->assertSame('exception', $event->getName());
+        $this->assertSame(ResponseException::class, $event->getAttributes()->get(TraceAttributes::EXCEPTION_TYPE));
+        $this->assertSame('HTTP status code 400 (Bad Request)', $event->getAttributes()->get(TraceAttributes::EXCEPTION_MESSAGE));
+        $this->assertSame(['text/plain; charset=utf-8'], $span->getAttributes()->get(sprintf('%s.%s', TraceAttributes::HTTP_RESPONSE_HEADER, 'content-type')));
+    }
+
+    public function test_rejected_promise_with_unknown_exception(): void
+    {
+        $this->browser->request('GET', 'http://example.com/unknown_error')->then(null, function () {});
+
+        $span = $this->storage->offsetGet(0);
+        $this->assertSame(StatusCode::STATUS_ERROR, $span->getStatus()->getCode());
+        $this->assertSame('Exception', $span->getAttributes()->get(TraceAttributes::ERROR_TYPE));
+        $event = $span->getEvents()[0];
+        $this->assertSame('exception', $event->getName());
+        $this->assertSame('Exception', $event->getAttributes()->get(TraceAttributes::EXCEPTION_TYPE));
+        $this->assertSame('Unknown', $event->getAttributes()->get(TraceAttributes::EXCEPTION_MESSAGE));
+    }
+
+    public function test_can_register(): void
+    {
+        $this->expectNotToPerformAssertions();
+
+        ReactPHPInstrumentation::register();
+    }
+
+    public function test_bail_on_noop(): void
+    {
+        $scope = Configurator::createNoop()->activate();
+        $this->browser->request('GET', 'http://example.com/success')->then();
+        $scope->detach();
+
+        $this->assertCount(0, $this->storage);
+    }
+}
diff --git a/src/Instrumentation/ReactPHP/tests/Unit/.gitkeep b/src/Instrumentation/ReactPHP/tests/Unit/.gitkeep
new file mode 100644
index 000000000..e69de29bb