About MCP Config Builder

What is this?

MCP Config Builder is a free, fully client-side web tool for creating, editing, and validating Model Context Protocol (MCP) configuration files. It supports the config formats used by Claude Desktop, Cursor, Windsurf, and ChatGPT.

Everything runs in your browser — no config data is ever sent to a server. Your server names, commands, environment variables, and API keys stay on your machine.

Why was it built?

MCP configuration files are simple JSON, but hand-editing them is error-prone. A missing comma, a string instead of an array for args, or a number instead of a string for env values can silently break your setup.

This tool gives you a visual editor with real-time validation, shareable URLs, and pre-built templates so you can get your MCP servers running in seconds.

How does validation work?

The tool uses a hand-authored JSON Schema (Draft-07) that is automatically checked against the latest MCP specification release. Validation runs entirely client-side using the AJV library — zero network requests are made during validation.

Technology

• Framework: Astro 6 with Preact islands
• Styling: Tailwind CSS v4
• Validation: AJV (client-side JSON Schema validator)
• URL state: Base64-encoded state in query parameters
• Hosting: Static site — no server, no database