diff --git a/CLAUDE.md b/CLAUDE.md
index d004756e..df759003 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -292,7 +292,8 @@ When dispatching subagents:
 
 - **Project Docs**: `docs/` (Sphinx RST format)
 - **Docker Guide**: `docs/docker-setup.md`
-- **API Docs**: http://localhost:8000/api/swagger (when running)
+- **API Docs (Scalar)**: http://localhost:8000/api/scalar (default, modern UI)
+- **API Docs (Swagger)**: http://localhost:8000/api/swagger (fallback)
 - **External**:
   - discord.py: https://discordpy.readthedocs.io/
   - Litestar: https://docs.litestar.dev/
diff --git a/README.md b/README.md
index 196065f9..230fbc32 100644
--- a/README.md
+++ b/README.md
@@ -57,7 +57,8 @@ make docker-up
 
 # 4. Access the application
 # API: http://localhost:8000
-# API Docs: http://localhost:8000/api/swagger
+# API Docs (Scalar): http://localhost:8000/api/scalar
+# API Docs (Swagger): http://localhost:8000/api/swagger
 ```
 
 **📚 Full Docker Guide**: See [docs/docker-setup.md](docs/docker-setup.md) for comprehensive documentation including:
diff --git a/docs/web/api/lib/openapi.rst b/docs/web/api/lib/openapi.rst
index 2a7f5073..d2621e9a 100644
--- a/docs/web/api/lib/openapi.rst
+++ b/docs/web/api/lib/openapi.rst
@@ -4,5 +4,29 @@ openapi
 
 OpenAPI config
 
+The Byte Bot API uses `Scalar <https://scalar.com/>`_ as the default OpenAPI documentation UI,
+with Swagger UI available as a fallback option.
+
+Accessing the API Documentation
+--------------------------------
+
+* **Scalar UI (Default)**: http://localhost:8000/api/scalar
+* **Swagger UI (Fallback)**: http://localhost:8000/api/swagger
+* **OpenAPI Schema**: http://localhost:8000/api/openapi.json
+
+Custom Theme
+------------
+
+The Scalar UI uses a custom theme with Byte brand colors:
+
+* Primary: ``#42b1a8`` (Byte Teal)
+* Secondary: ``#7bcebc`` (Byte Blue)
+* Accent: ``#abe6d2`` (Byte Light Blue)
+
+The theme supports both light and dark modes with automatic detection.
+
+Configuration
+-------------
+
 .. automodule:: byte_api.lib.openapi
      :members:
diff --git a/services/api/src/byte_api/domain/web/resources/css/scalar-theme.css b/services/api/src/byte_api/domain/web/resources/css/scalar-theme.css
new file mode 100644
index 00000000..4a0fdbd8
--- /dev/null
+++ b/services/api/src/byte_api/domain/web/resources/css/scalar-theme.css
@@ -0,0 +1,107 @@
+/* Byte Brand Custom Theme for Scalar OpenAPI Documentation */
+
+/* Light Mode Variables */
+:root {
+  /* Primary accent color - Byte Teal */
+  --scalar-color-accent: #42b1a8;
+
+  /* Background colors */
+  --scalar-background-1: #ebebe9; /* byte-white base */
+  --scalar-background-2: #ffffff; /* slightly lighter */
+  --scalar-background-3: #d4d4d2; /* slightly darker */
+
+  /* Text colors */
+  --scalar-color-1: #0c0c0c; /* byte-dark primary text */
+  --scalar-color-2: #3c3c3c; /* medium text */
+  --scalar-color-3: #6c6c6c; /* light text */
+
+  /* Border color - Byte Blue secondary */
+  --scalar-border-color: #7bcebc;
+
+  /* Sidebar */
+  --scalar-sidebar-background-1: #42b1a8; /* byte-teal */
+  --scalar-sidebar-background-2: #7bcebc; /* byte-blue */
+  --scalar-sidebar-color-1: #ebebe9; /* light text on dark sidebar */
+  --scalar-sidebar-color-2: #ffffff; /* white text */
+  --scalar-sidebar-color-active: #abe6d2; /* byte-light-blue for active items */
+  --scalar-sidebar-border-color: #7bcebc;
+
+  /* Status colors from DaisyUI theme */
+  --scalar-color-green: #059669; /* success */
+  --scalar-color-yellow: #d4a35a; /* byte-orange warning */
+  --scalar-color-red: #fc7054; /* byte-red error */
+  --scalar-color-blue: #7bcebc; /* byte-blue info */
+
+  /* Additional accents */
+  --scalar-button-1: #42b1a8;
+  --scalar-button-1-hover: #389e96;
+  --scalar-button-2: #7bcebc;
+  --scalar-button-2-hover: #6ab8a8;
+}
+
+/* Dark Mode Variables */
+@media (prefers-color-scheme: dark) {
+  :root {
+    /* Primary accent - keep teal */
+    --scalar-color-accent: #42b1a8;
+
+    /* Background colors - inverted */
+    --scalar-background-1: #0c0c0c; /* byte-dark */
+    --scalar-background-2: #1a1a1a; /* slightly lighter */
+    --scalar-background-3: #2a2a2a; /* lighter still */
+
+    /* Text colors - inverted */
+    --scalar-color-1: #ebebe9; /* byte-white for text */
+    --scalar-color-2: #d4d4d2; /* medium text */
+    --scalar-color-3: #a4a4a2; /* light text */
+
+    /* Border color */
+    --scalar-border-color: #42b1a8;
+
+    /* Sidebar - darker in dark mode */
+    --scalar-sidebar-background-1: #0c0c0c;
+    --scalar-sidebar-background-2: #1a1a1a;
+    --scalar-sidebar-color-1: #ebebe9;
+    --scalar-sidebar-color-2: #ffffff;
+    --scalar-sidebar-color-active: #42b1a8;
+    --scalar-sidebar-border-color: #42b1a8;
+
+    /* Status colors remain consistent */
+    --scalar-color-green: #059669;
+    --scalar-color-yellow: #d4a35a;
+    --scalar-color-red: #fc7054;
+    --scalar-color-blue: #7bcebc;
+
+    /* Buttons in dark mode */
+    --scalar-button-1: #42b1a8;
+    --scalar-button-1-hover: #52c1b8;
+    --scalar-button-2: #7bcebc;
+    --scalar-button-2-hover: #8bdccc;
+  }
+}
+
+/* Force dark mode when .dark class is present */
+.dark {
+  --scalar-color-accent: #42b1a8;
+  --scalar-background-1: #0c0c0c;
+  --scalar-background-2: #1a1a1a;
+  --scalar-background-3: #2a2a2a;
+  --scalar-color-1: #ebebe9;
+  --scalar-color-2: #d4d4d2;
+  --scalar-color-3: #a4a4a2;
+  --scalar-border-color: #42b1a8;
+  --scalar-sidebar-background-1: #0c0c0c;
+  --scalar-sidebar-background-2: #1a1a1a;
+  --scalar-sidebar-color-1: #ebebe9;
+  --scalar-sidebar-color-2: #ffffff;
+  --scalar-sidebar-color-active: #42b1a8;
+  --scalar-sidebar-border-color: #42b1a8;
+  --scalar-color-green: #059669;
+  --scalar-color-yellow: #d4a35a;
+  --scalar-color-red: #fc7054;
+  --scalar-color-blue: #7bcebc;
+  --scalar-button-1: #42b1a8;
+  --scalar-button-1-hover: #52c1b8;
+  --scalar-button-2: #7bcebc;
+  --scalar-button-2-hover: #8bdccc;
+}
diff --git a/services/api/src/byte_api/lib/openapi.py b/services/api/src/byte_api/lib/openapi.py
index 0322eb65..43cbacd7 100644
--- a/services/api/src/byte_api/lib/openapi.py
+++ b/services/api/src/byte_api/lib/openapi.py
@@ -3,9 +3,11 @@
 from __future__ import annotations
 
 from litestar.openapi.config import OpenAPIConfig
+from litestar.openapi.plugins import SwaggerRenderPlugin
 from litestar.openapi.spec import Contact
 
 from byte_api.lib import settings
+from byte_api.lib.scalar_theme import create_scalar_plugin
 
 __all__ = ("config",)
 
@@ -17,8 +19,11 @@
     version=settings.openapi.VERSION,
     contact=Contact(name=settings.openapi.CONTACT_NAME, email=settings.openapi.CONTACT_EMAIL),
     use_handler_docstrings=True,
-    root_schema_site="swagger",
     path=settings.openapi.PATH,
+    render_plugins=[
+        create_scalar_plugin(),
+        SwaggerRenderPlugin(path="/swagger"),
+    ],
 )
 """OpenAPI config for the project.
 See :class:`OpenAPISettings <.settings.OpenAPISettings>` for configuration.
diff --git a/services/api/src/byte_api/lib/scalar_theme.py b/services/api/src/byte_api/lib/scalar_theme.py
new file mode 100644
index 00000000..382345de
--- /dev/null
+++ b/services/api/src/byte_api/lib/scalar_theme.py
@@ -0,0 +1,19 @@
+"""Custom Scalar OpenAPI theme with Byte branding."""
+
+from __future__ import annotations
+
+from litestar.openapi.plugins import ScalarRenderPlugin
+
+__all__ = ("create_scalar_plugin",)
+
+
+def create_scalar_plugin() -> ScalarRenderPlugin:
+    """Create a Scalar plugin with custom Byte branding.
+
+    Returns:
+        Configured ScalarRenderPlugin with custom CSS
+    """
+    return ScalarRenderPlugin(
+        path="/scalar",
+        css_url="/static/css/scalar-theme.css",
+    )
diff --git a/tests/unit/api/test_openapi.py b/tests/unit/api/test_openapi.py
index 755d6945..243d2147 100644
--- a/tests/unit/api/test_openapi.py
+++ b/tests/unit/api/test_openapi.py
@@ -20,6 +20,8 @@
     "test_openapi_config_created",
     "test_openapi_contact_info",
     "test_openapi_includes_all_endpoints",
+    "test_openapi_render_plugins_configured",
+    "test_openapi_scalar_primary_plugin",
     "test_openapi_schema_generation",
     "test_openapi_security_schemes",
     "test_openapi_servers_configured",
@@ -58,9 +60,13 @@ def test_openapi_uses_handler_docstrings() -> None:
     assert openapi.config.use_handler_docstrings is True
 
 
-def test_openapi_root_schema_site() -> None:
-    """Test OpenAPI root schema site is set to Swagger."""
-    assert openapi.config.root_schema_site == "swagger"
+def test_openapi_render_plugins_configured() -> None:
+    """Test OpenAPI render plugins are configured with Scalar and Swagger."""
+    assert openapi.config.render_plugins is not None
+    assert len(openapi.config.render_plugins) >= 2
+    plugin_types = [type(plugin).__name__ for plugin in openapi.config.render_plugins]
+    assert "ScalarRenderPlugin" in plugin_types
+    assert "SwaggerRenderPlugin" in plugin_types
 
 
 @pytest.mark.asyncio
@@ -330,9 +336,12 @@ def test_openapi_use_handler_docstrings_true() -> None:
     assert openapi.config.use_handler_docstrings is True
 
 
-def test_openapi_root_schema_site_swagger() -> None:
-    """Test root schema site is Swagger."""
-    assert openapi.config.root_schema_site == "swagger"
+def test_openapi_scalar_primary_plugin() -> None:
+    """Test Scalar is the primary render plugin."""
+    assert openapi.config.render_plugins is not None
+    assert len(openapi.config.render_plugins) > 0
+    first_plugin_type = type(openapi.config.render_plugins[0]).__name__
+    assert first_plugin_type == "ScalarRenderPlugin"
 
 
 def test_openapi_config_immutable() -> None: