MCP Auth Playground – Local Bridge

Overview

Bridges the hosted MCP Auth Playground to local MCP servers on localhost or Docker networks.

The MCP Auth Playground – Local Bridge is a companion extension for the MCP Auth Playground (https://mcp-auth.playground.gravitee.io), an interactive workshop that teaches the OAuth 2.1 authorization flow used by Model Context Protocol (MCP) servers. WHY IS THIS NEEDED? When using the playground from the hosted URL, your browser enforces the same-origin policy, preventing direct requests to localhost, 127.0.0.1, or Docker-internal hostnames. This extension acts as a lightweight in-browser proxy to bypass that restriction. HOW IT WORKS 1. The playground web app sends a request via window.postMessage 2. The extension's content script forwards it to the background service worker 3. The service worker performs the actual HTTP fetch (which can reach any URL) 4. The response is sent back to the playground All communication stays entirely within your browser. No data is sent to external servers. FEATURES • Zero configuration – auto-detected by the playground • Reach localhost, 127.0.0.1, and Docker-exposed ports • Request counter in the toolbar popup • Fully open source PERMISSIONS This extension requests host access to all URLs because users may connect to any MCP server. The extension ONLY makes requests when explicitly triggered through the playground UI — it never fetches anything on its own. SOURCE CODE https://github.com/gravitee-io/mcp-oauth-flow-workshop/tree/main/auth-playground-app/chrome-extension

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Details

Version
1.0.0
Updated
February 23, 2026
Flag concern
Offered by
dobl
Size
11.72KiB
Languages
English
Developer
Email
dorian.blanc@graviteesource.com
Non-trader
This developer has not identified itself as a trader. For consumers in the European Union, please note that consumer rights do not apply to contracts between you and this developer.

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