OpenGrok MCP Server — Claude Code MCP server: setup and code search
Connects an AI coding client to an OpenGrok index for symbol search, file reading, blame, history, and call relationships across large codebases.
claude mcp add --env OPENGROK_BASE_URL=<OPENGROK_BASE_URL> --env OPENGROK_USERNAME=<OPENGROK_USERNAME> --env OPENGROK_PASSWORD=<OPENGROK_PASSWORD> --env OPENGROK_VERIFY_SSL=<OPENGROK_VERIFY_SSL> --env OPENGROK_CODE_MODE=<OPENGROK_CODE_MODE> --transport stdio opengrok-mcp-server -- npx -y opengrok-mcp-serverWhat OpenGrok MCP Server does
OpenGrok MCP Server gives an MCP client access to an OpenGrok instance through its REST API, with a web fallback. An agent can search source and history, locate files and symbols, read selected code ranges, inspect blame, review file history, and trace calls or dependencies.
Code Mode exposes opengrok_api and opengrok_execute. The agent writes one JavaScript script for a multi-step investigation, while intermediate results stay inside the sandbox. Two files, active-task.md and investigation-log.md, can retain investigation state between turns. A working OpenGrok URL, username, and password are required for setup.
What it helps with
- find symbol definitions and references
- read a selected range from a large file
- inspect who changed a line or file
- trace callers of a service or method
- map dependencies before a refactor
Example prompts for the agent
- Find every reference to
authenticateand group the results by file. - Read the implementation of
PaymentService, then inspect its change history and authors. - Trace callers of
parseConfigand record the findings ininvestigation-log.md.
How to install OpenGrok MCP Server
Platform CLI
claude mcp add --env OPENGROK_BASE_URL=<OPENGROK_BASE_URL> --env OPENGROK_USERNAME=<OPENGROK_USERNAME> --env OPENGROK_PASSWORD=<OPENGROK_PASSWORD> --env OPENGROK_VERIFY_SSL=<OPENGROK_VERIFY_SSL> --env OPENGROK_CODE_MODE=<OPENGROK_CODE_MODE> --transport stdio opengrok-mcp-server -- npx -y opengrok-mcp-serverReplace <…> with your own values. 26 more environment variables are in the server README
Platform CLI
codex mcp add opengrok-mcp-server --env OPENGROK_BASE_URL=<OPENGROK_BASE_URL> --env OPENGROK_USERNAME=<OPENGROK_USERNAME> --env OPENGROK_PASSWORD=<OPENGROK_PASSWORD> --env OPENGROK_VERIFY_SSL=<OPENGROK_VERIFY_SSL> --env OPENGROK_CODE_MODE=<OPENGROK_CODE_MODE> -- npx -y opengrok-mcp-serverReplace <…> with your own values. 26 more environment variables are in the server README
Config file
{
"mcpServers": {
"opengrok-mcp-server": {
"command": "npx",
"args": [
"-y",
"opengrok-mcp-server"
],
"env": {
"OPENGROK_BASE_URL": "<OPENGROK_BASE_URL>",
"OPENGROK_USERNAME": "<OPENGROK_USERNAME>",
"OPENGROK_PASSWORD": "<OPENGROK_PASSWORD>",
"OPENGROK_VERIFY_SSL": "<OPENGROK_VERIFY_SSL>",
"OPENGROK_CODE_MODE": "<OPENGROK_CODE_MODE>"
}
}
}
}Replace <…> with your own values. 26 more environment variables are in the server README
Config file
{
"servers": {
"opengrok-mcp-server": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"opengrok-mcp-server"
],
"env": {
"OPENGROK_BASE_URL": "<OPENGROK_BASE_URL>",
"OPENGROK_USERNAME": "<OPENGROK_USERNAME>",
"OPENGROK_PASSWORD": "<OPENGROK_PASSWORD>",
"OPENGROK_VERIFY_SSL": "<OPENGROK_VERIFY_SSL>",
"OPENGROK_CODE_MODE": "<OPENGROK_CODE_MODE>"
}
}
}
}Replace <…> with your own values. 26 more environment variables are in the server README
Platform CLI
gemini mcp add -e OPENGROK_BASE_URL=<OPENGROK_BASE_URL> -e OPENGROK_USERNAME=<OPENGROK_USERNAME> -e OPENGROK_PASSWORD=<OPENGROK_PASSWORD> -e OPENGROK_VERIFY_SSL=<OPENGROK_VERIFY_SSL> -e OPENGROK_CODE_MODE=<OPENGROK_CODE_MODE> opengrok-mcp-server npx -y opengrok-mcp-serverReplace <…> with your own values. 26 more environment variables are in the server README
Step by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about OpenGrok MCP Server
How do I install OpenGrok MCP Server in Claude Code?
Run `claude mcp add --env OPENGROK_BASE_URL=<OPENGROK_BASE_URL> --env OPENGROK_USERNAME=<OPENGROK_USERNAME> --env OPENGROK_PASSWORD=<OPENGROK_PASSWORD> --env OPENGROK_VERIFY_SSL=<OPENGROK_VERIFY_SSL> --env OPENGROK_CODE_MODE=<OPENGROK_CODE_MODE> --transport stdio opengrok-mcp-server -- npx -y opengrok-mcp-server`.
What does OpenGrok MCP Server do?
It lets an AI client query OpenGrok for source, symbols, references, blame, history, diffs, and call relationships. The client can investigate an indexed codebase through MCP.
What does the server need to connect?
You need an OpenGrok endpoint plus its username and password. Code Mode is available for running JavaScript investigations inside a sandbox.
