{"slug": "show-hn-synapse-local-codebase-indexer-and-mcp-server-for-claude-code", "title": "Show HN: Synapse – local codebase indexer and MCP server for Claude Code", "summary": "Synapse, a local codebase indexer and MCP server for Claude Code, launched on Hacker News. The tool indexes project files locally and provides instant code context to Claude without sending data to the cloud, supporting multiple MCP-compatible clients. It aims to eliminate the need for developers to manually paste code snippets when asking Claude about their codebase.", "body_md": "Synapse Give Claude instant knowledge of your codebase — local, private, no cloud.\n\nYou open Claude Code and ask: \"Add retry logic to my API client.\"\n\nWithout Synapse: Claude asks what your stack is. You paste 200 lines of code. You explain your conventions. You do this again tomorrow.\n\nWith Synapse: Claude says: \"Your API client in src/api/client.ts uses Axios with your custom RetryConfig interface — matching the pattern you used in payment.ts. Here's the implementation:\"\n\nSynapse watches your project folders, indexes them locally, and connects to Claude via MCP. Claude knows your codebase without you saying a word.\n\nInstall in 2 minutes pip install synapse-mcp\n\nsynapse init C:/Projects/myapp\n\nThen paste one line into your Claude Desktop config. Done.\n\nWhat it does Watches your project folders — indexes code, markdown, and config files automatically Stores everything locally — no API key required, nothing leaves your machine Connects to Claude via MCP — works with Claude Desktop, Cursor, and any MCP client Updates in real time — re-indexes files as you save them\n\nSupported tools Tool Status Claude Code ✅ Supported (primary target) Cursor ✅ Supported via MCP Continue ✅ Supported via MCP Claude Desktop chat 🔜 Coming in v0.2 Any MCP client ✅ Standard MCP protocol\n\nSupported file types .py .ts .tsx .js .jsx .go .rs .java .kt .rb .php .cs .swift .cpp .c .h .sh .ps1 .sql .tf .md .json .yaml .toml .env .graphql .proto · Dockerfile · Makefile · and more\n\nConnect to Claude Code After running synapse init , register Synapse as an MCP server:\n\nclaude mcp add synapse synapse-mcp\n\nThat's it. Restart claude and run /mcp to confirm synapse shows connected · 2 tools.\n\nClaude Desktop chat support is planned for v0.2 via SSE transport. Track progress in #12.\n\nCLI reference synapse init # Index a folder (run this first)\n\nsynapse status # Show what's indexed\n\nsynapse search # Search from the terminal\n\nsynapse wipe # Delete the local index\n\nConfiguration Synapse works out of the box with no config file required. To customize, create ~/.synapse/config.toml:\n\n[synapse]\n\nwatch_paths = [\"C:/Projects/myapp\", \"C:/Projects/clientwork\"]\n\nignore_patterns = [\"node_modules\", \".git\", \"dist\", \"*.pyc\"]\n\n[embedding]\n\nprovider = \"local\" # \"local\" (default, free, private) or \"openai\"\n\nchunk_size = 512\n\nchunk_overlap = 64\n\nLocal embeddings (default): Uses nomic-embed-text-v1.5 via sentence-transformers. Downloads ~400MB on first run. Free. Nothing leaves your machine.\n\nOpenAI embeddings (optional): Set provider = \"openai\" and OPENAI_API_KEY env var. Slightly better quality for natural language queries. Costs ~$0.00 for personal use.\n\nHow it works Your files → Synapse watches → Chunks text → Embeds locally → Stores in LanceDB\n\n```\n                                                                   ↓\n```\n\nClaude Desktop ←── MCP query ←── Synapse MCP server ←── Semantic search\n\nsynapse init walks your project and indexes every supported file The file watcher triggers incremental re-indexing on every save When you open Claude Desktop, the synapse-mcp server is available as a connected tool Claude calls recall(\"your question\") automatically before answering Relevant code snippets are injected into Claude's context window\n\nNo round trips to external servers. No accounts. No rate limits.\n\nFAQ Does my code leave my machine? No. With the default local embedding provider, every computation happens on your machine. The only network call is the initial model download (~400MB, cached permanently after that).\n\nWhat if I use the openai provider? Your code text is sent to OpenAI's API for embedding. If you work on sensitive or proprietary code, use the default local provider.\n\nHow is this different from Cursor's built-in indexing? Cursor's index lives inside Cursor only. Synapse works with Claude Desktop, Cursor, Continue, and any other MCP-compatible client — all from one index.\n\nHow is this different from ChatGPT Memory? ChatGPT Memory is locked to ChatGPT and stored on OpenAI's servers. Synapse works with any AI tool and stores everything locally.\n\nWill it index my .env files or secrets? Yes — it indexes .env files if they're in your watch path. If you don't want this, add .env to the ignore_patterns list in your config.\n\nCan I inspect what's in the index? Yes: synapse status shows counts, and synapse search lets you query it directly.\n\nHow do I remove a project from the index? Run synapse wipe to clear everything. Then run synapse init again with only the paths you want.\n\nRequirements Python 3.10+ 1 GB free disk space (for the embedding model cache) Claude Desktop (or any MCP client)\n\nContributing Synapse is MIT-licensed and welcomes contributions.\n\nGood first issues:\n\nAdd support for a new file type in synapse/ingestion/reader.py Improve chunking for a specific language Write integration tests\n\nTo contribute:\n\ngit clone [https://github.com/nrkoka786/synapse](https://github.com/nrkoka786/synapse)\n\ncd synapse\n\npip install -e \".[dev]\"\n\npytest tests/\n\nSee CONTRIBUTING.md for guidelines.\n\nRoadmap Core filesystem indexing Claude Code MCP integration Local embeddings (no API key) File watcher (incremental re-indexing) Claude Desktop chat support (SSE transport) — v0.2 Git log ingestion (commit messages + PR descriptions) Markdown + PDF document indexing synapse search TUI with rich output Windows installer (.exe) macOS App Synapse Cloud (encrypted cross-device sync) — planned Team Synapse (shared org context) — planned\n\nLicense MIT © 2026 NR · github.com/nrkoka786/synapse", "url": "https://wpnews.pro/news/show-hn-synapse-local-codebase-indexer-and-mcp-server-for-claude-code", "canonical_source": "https://github.com/nrkoka786/synapse", "published_at": "2026-07-19 03:35:20+00:00", "updated_at": "2026-07-19 03:51:01.986065+00:00", "lang": "en", "topics": ["developer-tools", "ai-tools", "artificial-intelligence", "large-language-models"], "entities": ["Synapse", "Claude Code", "Claude Desktop", "Cursor", "Continue", "MCP", "LanceDB", "OpenAI"], "alternates": {"html": "https://wpnews.pro/news/show-hn-synapse-local-codebase-indexer-and-mcp-server-for-claude-code", "markdown": "https://wpnews.pro/news/show-hn-synapse-local-codebase-indexer-and-mcp-server-for-claude-code.md", "text": "https://wpnews.pro/news/show-hn-synapse-local-codebase-indexer-and-mcp-server-for-claude-code.txt", "jsonld": "https://wpnews.pro/news/show-hn-synapse-local-codebase-indexer-and-mcp-server-for-claude-code.jsonld"}}