Your coding standards, always in context

An open-source MCP server that gives your AI assistant semantic search over your personal documentation and coding guidelines. 100% offline.

Get Started View on GitHub
terminal
$ c42 add ./my-standards --name rules --priority 0.9
✓ Source 'rules' added
$ c42 index
✓ Indexed 42 chunks from 1 source
$ c42 serve
✓ MCP server running▌

The problem

Standards get lost

Your AI assistant doesn't know your team's coding conventions. Every session starts from zero.

Docs are scattered

Guidelines live in wikis, READMEs, and Notion pages. None of it reaches your AI tools.

Context windows fill up

Pasting entire docs into prompts wastes tokens and dilutes focus.

The solution

Context42 indexes your documentation locally and serves the most relevant chunks to your AI assistant via MCP — automatically, semantically, and privately.

Your Docs
c42 index
Vector DB
MCP
Claude

Features

100% Offline

Runs entirely on your machine. No API calls, no cloud, no data leaving your computer.

Semantic Search

Finds relevant content by meaning, not just keywords. Powered by local embeddings.

Priority System

Weight your personal rules higher than reference docs. Control what matters most.

MCP Native

Built for the Model Context Protocol. Works with Claude Desktop out of the box.

Multi-format

Index Markdown and reStructuredText files. More formats coming soon.

Smart Indexing

Content-hash based deduplication. Re-run safely without duplicating data.

How it works

1

Add your sources

Point Context42 to your documentation directories.

c42 add ./my-standards --name standards --priority 0.9
c42 add ./docs --name reference --priority 0.5
2

Index

Context42 chunks your docs and creates local vector embeddings.

c42 index
3

Manage your sources

List, adjust priorities, search, or remove sources at any time.

c42 list
c42 set-priority standards 1.0
c42 search "error handling"
c42 status
4

Connect to Claude

Start the MCP server and configure Claude Desktop.

c42 serve

Get started in under a minute 

# Install with pipx (recommended), uvx, or pip
pipx install context42-io

# Add your docs, index, and serve
c42 add ./my-docs --name my-docs
c42 index
c42 serve

Claude Desktop configuration

claude_desktop_config.json 
{
  "mcpServers": {
    "context42": {
      "command": "c42",
      "args": ["serve"]
    }
  }
}
MIT License

Free & Open Source

Context42 is free and open source, licensed under MIT.

Star us on GitHub

Contributions welcome