CodeGraph

AST-based code knowledge graph. Parses source code across 10 languages, builds a Neo4j graph of classes, functions, endpoints, DB models, imports, and call chains — then exposes it all via MCP for Claude.

Why

Documentation gets outdated. Code doesn't. CodeGraph lets you query business logic directly from source code.

What it extracts

12 node types: Repository, Service, File, Module, Class, Function, Variable, Endpoint, DatabaseTable, Event, ExternalAPI, BusinessRule

15 relationship types: CONTAINS_FILE, DEFINES, CONTAINS, HAS_METHOD, HAS_FIELD, EXTENDS, IMPLEMENTS, CALLS, CALLS_EXTERNAL, EXPOSES, HANDLED_BY, READS_FROM, WRITES_TO, PUBLISHES, SUBSCRIBES_TO, IMPORTS

Supported languages

Swift, Kotlin, PHP, Python, JavaScript, TypeScript, Go, Dart, C#

Setup

Prerequisites

• Python 3.12+
• uv
• Docker

Install

git clone https://github.com/mustafo/CodeGraph.git
cd CodeGraph
uv sync

Start Neo4j

docker compose up -d

Neo4j Browser: http://localhost:7474 (neo4j / codegraph)

Usage

Index repositories

# Single repo
uv run main.py index /path/to/your-repo
# With a custom name
uv run main.py index /path/to/your-repo --name my-service
# Multiple repos
uv run main.py index \
/path/to/repo-one --name backend \
/path/to/repo-two --name mobile

Indexing is incremental by default — only changed files get re-parsed.

Re-index all

uv run reindex.py

Re-indexes every previously indexed repo (incremental).

MCP server (Claude Desktop)

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
"mcpServers": {
"code-graph": {
"command": "uv",
"args": ["--directory", "/path/to/CodeGraph", "run", "main.py"]
}
}
}

MCP server (Claude Code)

claude mcp add --transport stdio -s user code-graph -- uv --directory /path/to/CodeGraph run main.py

Available MCP tools

Tool	Description
index_repository	Index a local git repo into the graph
query_code	Execute raw Cypher against the graph
find_callers	Find all functions that call a given function
find_dependencies	Find what a service depends on
trace_endpoint	Trace an API endpoint through the call graph
list_services	List all indexed repositories
search_code	Fuzzy search for any code entity by name
graph_stats	Node and relationship counts

Architecture

Claude Desktop / Claude Code
│
MCP (stdio)
│
main.py (FastMCP)
│
code_graph/
├── parser.py ← tree-sitter AST parsing
├── languages.py ← per-language node type mappings
├── schema.py ← CodeNode / CodeRelationship
├── neo4j_store.py ← async Neo4j client
└── indexer.py ← repo walker + orchestrator
│
Neo4j (Docker)

Example queries via Claude

• "What services are indexed?"
• "Who calls processPayment?"
• "Trace POST /api/checkout through the call graph"
• "What classes extend BaseRepository?"
• "Show me all REST endpoints in the payments service"