diff --git a/src/ChromeDevtoolsProtocol/Instance/Instance.php b/src/ChromeDevtoolsProtocol/Instance/Instance.php
index e5b51102..4e80876b 100644
--- a/src/ChromeDevtoolsProtocol/Instance/Instance.php
+++ b/src/ChromeDevtoolsProtocol/Instance/Instance.php
@@ -58,7 +58,7 @@ public function __construct(string $host, int $port, ?ClientInterface $httpClien
 
 	public function tabs(ContextInterface $ctx): array
 	{
-		$response = $this->httpClient->request("POST", "http://{$this->host}:{$this->port}/json/list", [
+		$response = $this->httpClient->request("GET", "http://{$this->host}:{$this->port}/json/list", [
 			"timeout" => $ctx->getDeadline() !== null ? $ctx->deadlineFromNow() : 0,
 		]);
 
@@ -73,7 +73,7 @@ public function tabs(ContextInterface $ctx): array
 	public function open(ContextInterface $ctx, ?string $url = null): Tab
 	{
 		$response = $this->httpClient->request(
-			"POST",
+			"PUT",
 			"http://{$this->host}:{$this->port}/json/new" . ($url !== null ? "?" . urlencode($url) : ""),
 			[
 				"timeout" => $ctx->getDeadline() !== null ? $ctx->deadlineFromNow() : 0,
@@ -84,7 +84,7 @@ public function open(ContextInterface $ctx, ?string $url = null): Tab
 
 	public function version(ContextInterface $ctx): Version
 	{
-		$response = $this->httpClient->request("POST", "http://{$this->host}:{$this->port}/json/version", [
+		$response = $this->httpClient->request("GET", "http://{$this->host}:{$this->port}/json/version", [
 			"timeout" => $ctx->getDeadline() !== null ? $ctx->deadlineFromNow() : 0,
 		]);
 		return Version::fromJson(json_decode($response->getBody()->getContents()));
@@ -160,7 +160,7 @@ public function createSession(ContextInterface $ctx, string $url = "about:blank"
 	 */
 	public function activateTabById(ContextInterface $ctx, string $id): void
 	{
-		$this->httpClient->request("POST", "http://{$this->host}:{$this->port}/json/activate/{$id}", [
+		$this->httpClient->request("GET", "http://{$this->host}:{$this->port}/json/activate/{$id}", [
 			"timeout" => $ctx->getDeadline() !== null ? $ctx->deadlineFromNow() : 0,
 		]);
 	}
@@ -170,7 +170,7 @@ public function activateTabById(ContextInterface $ctx, string $id): void
 	 */
 	public function closeTabById(ContextInterface $ctx, string $id): void
 	{
-		$this->httpClient->request("POST", "http://{$this->host}:{$this->port}/json/close/{$id}", [
+		$this->httpClient->request("GET", "http://{$this->host}:{$this->port}/json/close/{$id}", [
 			"timeout" => $ctx->getDeadline() !== null ? $ctx->deadlineFromNow() : 0,
 		]);
 	}
diff --git a/src/ChromeDevtoolsProtocol/Instance/Launcher.php b/src/ChromeDevtoolsProtocol/Instance/Launcher.php
index 937d98fd..50cf6410 100644
--- a/src/ChromeDevtoolsProtocol/Instance/Launcher.php
+++ b/src/ChromeDevtoolsProtocol/Instance/Launcher.php
@@ -20,9 +20,10 @@ class Launcher
 	const DEFAULT_LINUX_EXECUTABLE = "google-chrome";
 	const DEFAULT_WINDOWS_EXECUTABLE = "chrome";
 
-	public static $defaultArgs = [
-		"--headless",
-	];
+    public static $defaultArgs = [
+        "--headless",
+        "--remote-allow-origins=http://127.0.0.1"
+    ];
 
 	/** @var string */
 	private $executable;
@@ -40,16 +41,11 @@ class Launcher
 	private $input;
 
 	/**
-	 * @param int $port If port <= 0, random port number is generated.
-	 * @throws \Exception
+	 * @param int $port If port <= 0, random available port is used.
 	 */
 	public function __construct($port = 0)
 	{
-		if ($port <= 0) {
-			$port = random_int(1024 + 1, 65535);
-		}
-
-		$this->port = $port;
+		$this->port = max(0, $port);
 	}
 
 	/**
@@ -212,6 +208,10 @@ private function launchWithExecutable(ContextInterface $ctx, string $executable,
 		$temporaryUserDataDir = null;
 		if (!$foundUserDataDir) {
 			$temporaryUserDataDir = sys_get_temp_dir() . DIRECTORY_SEPARATOR . "chrome-profile-" . $this->port;
+			if ($this->port === 0) {
+				$temporaryUserDataDir .= "-" . bin2hex(random_bytes(8));
+			}
+
 			$fs->mkdir($temporaryUserDataDir);
 			$args[] = "--user-data-dir=" . $temporaryUserDataDir;
 		}
@@ -226,6 +226,16 @@ private function launchWithExecutable(ContextInterface $ctx, string $executable,
 			);
 			$process->start();
 
+			if ($this->port === 0) {
+				$process->waitUntil(function ($type, $buffer)  {
+					if (preg_match('~DevTools listening on ws://.+:(\d+)/devtools~', $buffer, $m)) {
+						$this->port = (int)$m[1];
+						return true;
+					}
+					return false;
+				});
+			}
+
 			$instance = new ProcessInstance($process, $temporaryUserDataDir, $this->port);
 
 			while (true) {