Regex Explainer MCP MCP server

This MCP server exposes the Regex Explainer engine, allowing AI agents to explain regular expressions in plain English and detect catastrophic backtracking risks. It serves as one of four surfaces (alongside web, markdown, and JSON API) for the same underlying pure function, requiring no authentication and supporting free usage with rate limits.

Endpoint and access

No sign-in: your client connects and lists tools immediately, with no account or key.

No sign-inEndpoint checked 2026-10-05Operated by Gumball Tools

MCP endpoint (Streamable HTTP)

https://regex-explainer.gumballtools.com/api/mcp

Vendor documentation

What you can do with it

Explain a regex pattern in plain English
Detect catastrophic backtracking risk in regex
Validate regex syntax via agent tools

Tools advertised by the last live check:

explain_regex

Connect from your client

Each snippet registers the same endpoint; pick the client you use.

This server is operated by the named third party. Listing and endpoint checks are not an endorsement or a security audit. Review the operator's permissions, terms, and data handling before connecting. How listings are checked and corrected.

Claude Code

Run this once in a terminal. It registers a Streamable HTTP server. Use --scope project to write .mcp.json for the repo.

Claude Code configuration

claude mcp add --transport http regex-explainer-mcp https://regex-explainer.gumballtools.com/api/mcp

Codex

Run this once. Codex stores MCP servers in ~/.codex/config.toml (or .codex/config.toml in a trusted project).

Codex configuration

codex mcp add regex-explainer-mcp --url https://regex-explainer.gumballtools.com/api/mcp

Cursor

Merge this server into .cursor/mcp.json in your project, then enable regex-explainer-mcp in your MCP settings.

Cursor configuration

{
  "mcpServers": {
    "regex-explainer-mcp": {
      "url": "https://regex-explainer.gumballtools.com/api/mcp"
    }
  }
}

Cline

Merge this into cline_mcp_settings.json (Cline → MCP Servers → Configure). The type must be streamableHttp for a remote HTTP server.

Cline configuration

{
  "mcpServers": {
    "regex-explainer-mcp": {
      "type": "streamableHttp",
      "url": "https://regex-explainer.gumballtools.com/api/mcp",
      "disabled": false
    }
  }
}

VS Code

Merge this server into .vscode/mcp.json. Use MCP: List Servers to start regex-explainer-mcp and inspect its tools.

VS Code configuration

{
  "servers": {
    "regex-explainer-mcp": {
      "type": "http",
      "url": "https://regex-explainer.gumballtools.com/api/mcp"
    }
  }
}

Gemini CLI

Run this once. It writes .gemini/settings.json in the current project; pass --scope user for ~/.gemini/settings.json.

Gemini CLI configuration

gemini mcp add --transport http regex-explainer-mcp https://regex-explainer.gumballtools.com/api/mcp

Claude Desktop

Merge this into claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/, Windows: %APPDATA%\Claude\), then restart Claude Desktop.

Claude Desktop configuration

{
  "mcpServers": {
    "regex-explainer-mcp": {
      "url": "https://regex-explainer.gumballtools.com/api/mcp"
    }
  }
}

Windsurf

Merge this into ~/.codeium/windsurf/mcp_config.json, then refresh MCP in Cascade. Windsurf remote servers use serverUrl, not url.

Windsurf configuration

{
  "mcpServers": {
    "regex-explainer-mcp": {
      "serverUrl": "https://regex-explainer.gumballtools.com/api/mcp"
    }
  }
}

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