DevToolsPlugin

Exposes Dev Proxy messages, and information about intercepted requests and responses in Chrome DevTools. Supports both HTTP requests and STDIO communication.

Configuration example

{
  "$schema": "https://raw.githubusercontent.com/dotnet/dev-proxy/main/schemas/v4.0.0/rc.schema.json",
  "plugins": [
    {
      "name": "DevToolsPlugin",
      "enabled": true,
      "pluginPath": "~appFolder/plugins/DevProxy.Plugins.dll",
      "configSection": "devTools"
    }
  ],
  "devTools": {
    "$schema": "https://raw.githubusercontent.com/dotnet/dev-proxy/main/schemas/v4.0.0/devtoolsplugin.schema.json",
    "preferredBrowser": "Edge"
  }
}

Configuration properties

Command line options

None

Remarks

The plugin listens for Dev Tools connections on the IP address that Dev Proxy uses, which you set using the --ip-address option. When you set it to 0.0.0.0 or ::, the plugin listens on all interfaces and the Dev Tools URL points to 127.0.0.1. On Windows, listening on all interfaces requires admin rights or a URL ACL. If the plugin can't listen on all interfaces, it listens on 127.0.0.1 instead, so you can only connect Dev Tools from the same machine.

To protect intercepted traffic, the plugin only accepts Dev Tools connections that:

• use the URL that Dev Proxy launches or logs. The URL contains a random token that Dev Proxy generates each time it starts.
• come from the Chrome DevTools frontend, either devtools://devtools, http://localhost:9222, or http://127.0.0.1:9222.

The plugin rejects other connections with 403 Forbidden and logs a warning.

To use the plugin when Dev Proxy runs in a container, a dev container, or GitHub Codespaces, set port to a fixed port, set launchBrowser to false, and publish or forward the port to your machine. For more information, see Inspect requests when Dev Proxy runs in a container.

Known issues

Dev Tools don't open in Microsoft Edge on Windows

You use Dev Proxy on Windows and configure it to use Microsoft Edge to display Dev Tools. After you start Dev Proxy, it starts the inspector but Dev Tools don't open or they open empty.

To fix this issue:

1. Open Microsoft Edge
2. Go to Settings
3. Open System and performance
4. Disable Startup boost
5. Close all Microsoft Edge windows and processes
6. Start Dev Proxy

STDIO support

When using the DevToolsPlugin with the stdio command, you can inspect STDIN/STDOUT/STDERR communication in Chrome DevTools:

• Messages appear with stdio://command-name URLs
• Requests show as STDIN method
• Responses show as STDOUT (200 status) or STDERR (500 status)
• Message bodies are formatted as JSON when applicable
• Timing information is available for each request/response pair

Configuration example for STDIO

{
  "$schema": "https://raw.githubusercontent.com/dotnet/dev-proxy/main/schemas/v4.0.0/rc.schema.json",
  "plugins": [
    {
      "name": "DevToolsPlugin",
      "enabled": true,
      "pluginPath": "~appFolder/plugins/DevProxy.Plugins.dll",
      "configSection": "devTools"
    }
  ],
  "devTools": {
    "$schema": "https://raw.githubusercontent.com/dotnet/dev-proxy/main/schemas/v4.0.0/devtoolsplugin.schema.json",
    "preferredBrowser": "Edge"
  }
}

Then run:

devproxy stdio npx -y @modelcontextprotocol/server-filesystem

Next step