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MCP Config Validator

Paste your mcpServers (or VS Code servers) JSON to catch mistakes before your AI client silently fails to load a server.

  • Free
  • No sign-in
  • Runs in your browser

1 Paste your config

config.json
Valid JSON

2 Results

Checked as Claude Desktop / Claude Code

Looks good

Valid Claude Desktop / Claude Code config. Save it and fully restart your client.

Formatted
{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-github"
      ],
      "env": {
        "GITHUB_PERSONAL_ACCESS_TOKEN": "ghp_yourtoken"
      }
    }
  }
}

Why validate before restarting your client

A single misplaced comma or a missing command field is enough to make an MCP client quietly skip a server on startup, usually with no error message pointing at the actual cause. Tracking that down by trial and error — edit, save, fully restart the client, check if it worked — is slow.

Frequently asked questions

The most common syntax errors are trailing commas after the last server entry, unescaped backslashes in Windows file paths, and unquoted property keys or strings.

Environment variables are specified under the env object as key-value string pairs, for example: "env": { "API_KEY": "secret_123" }.

In JSON, backslashes must be escaped with double backslashes (e.g., "C:\\Program Files\\node\\node.exe") or replaced with forward slashes ("C:/Program Files/node/node.exe").

No. Validation runs 100% locally inside your web browser. API keys, secrets, and path details pasted into this tool never leave your device.
Audit for placeholder keysMCP troubleshooting guide