Rexact

Developer Tools npm v0.1.2

Verify, explain and audit regexes (ReDoS, engine compatibility) offline.

View source ↗ Website ↗ Generate config for multiple servers More servers

Install

Run one of the commands below, then pick your client in the next section.

npm
npx -y rexact-mcp

Setup by client

Pick your client — the config below is generated for this server (local stdio).

claude_desktop_config.json

{
  "mcpServers": {
    "rexact-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "rexact-mcp"
      ],
      "env": {
        "ANTHROPIC_API_KEY": "<YOUR_ANTHROPIC_API_KEY>"
      }
    }
  }
}

Format verified against the official Claude Desktop docs ↗.

terminal

claude mcp add --env ANTHROPIC_API_KEY=<YOUR_ANTHROPIC_API_KEY> rexact-mcp -- npx -y rexact-mcp

Format verified against the official Claude Code docs ↗.

.cursor/mcp.json

{
  "mcpServers": {
    "rexact-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "rexact-mcp"
      ],
      "env": {
        "ANTHROPIC_API_KEY": "<YOUR_ANTHROPIC_API_KEY>"
      }
    }
  }
}

Format verified against the official Cursor docs ↗.

.vscode/mcp.json

{
  "servers": {
    "rexact-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "rexact-mcp"
      ],
      "env": {
        "ANTHROPIC_API_KEY": "<YOUR_ANTHROPIC_API_KEY>"
      }
    }
  }
}

Format verified against the official VS Code docs ↗.

mcp_config.json

{
  "mcpServers": {
    "rexact-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "rexact-mcp"
      ],
      "env": {
        "ANTHROPIC_API_KEY": "<YOUR_ANTHROPIC_API_KEY>"
      }
    }
  }
}

Format verified against the official Windsurf docs ↗.

Environment variables

Defined in the server's official registry manifest. Required secrets are shown as <YOUR_…> placeholders in the configs above.

ANTHROPIC_API_KEY secret — Optional. Only needed by the generate_regex tool; the four other tools work offline without it.

About this server

Distributed as npm, listed under Developer Tools. Review our MCP security guide before granting access to real data.

Frequently asked questions

How do I install Rexact?

Run the install command shown above, then paste the config for your client (Claude Desktop, Claude Code, Cursor, VS Code or Windsurf) into its MCP settings and restart the client.

Is Rexact free to use?

The MCP server itself is free to install. The source is public on https://github.com/Nicolasmar91/rexact-mcp. Any third-party service it calls may require its own API key and account.

Which clients support Rexact?

Any MCP-compatible client can use it, including Claude Desktop, Claude Code, Cursor, VS Code, Windsurf and custom agents.

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