Membrain is a memory ledger you run on your own machine — or open free in the cloud. You write to it from a paper-and-ink web UI; your agents write to it over MCP. What one remembers, all of them know. Self-hosted, everything is a single SQLite file on your disk; hosted, the same ledger lives at membrain.devlune.in and agents connect with API keys.
Then one word — membrain — brings up the ledger, the REST API and a live MCP endpoint.
Eight tools — save, search, update, list, and a one-call session-start digest. Claude Code, Claude Desktop, Cursor: anything that speaks the protocol writes into the same ledger, and every entry is stamped with who wrote it.
Hybrid search: sqlite-vec embeddings and FTS5 keywords merged with reciprocal rank fusion, plus a gentle recency boost. The embedding model runs locally on CPU — recall works with zero API keys, offline.
A local Ollama — or any pasted cloud key — organizes the store into topics, drafts titles, distills dropped PDFs into candidate entries. Every AI change is staged for your approval. Nothing edits your memory silently.
The whole store is a single SQLite file on your disk. A backup is a file copy; a snapshot happens on every boot; a markdown export turns the ledger into a git-diffable folder. No accounts, no cloud, no telemetry.
The clerk draws your store as a constellation — people, projects, tools and how they connect, laid out with real physics. Built on request, never used for retrieval; a map, not a database.
It also manages agent skill files on disk and discovers memory your agents already keep, importing it hash-tracked so nothing files twice. The web UI, REST API and MCP endpoint are one process, one port.
Agents connect at /mcp — Streamable HTTP or stdio — and get a small, sharp toolset:
save_memorywrite a fact into the ledgersave_memoriesfile several at oncesearch_memoryhybrid semantic + keyword recallmemory_contextone-call session-start briefingget_memory / list_memoriesread entriesupdate_memory / delete_memorycorrect the recordIt binds to localhost. The network boundary is the security model — no logins bolted onto a personal tool.
Anything an agent writes is visible and editable in the web UI. No hidden tables, no silent ghosts.
Local embeddings, local LLM, local file. Cloud keys are an option, never a requirement.
UI, REST and MCP call the same core functions. Your agents get no secret door.
Crafted in the dark. Shipped to the world. — DevLune