# Callosium

> Callosium gives every AI you use one shared memory. It lives in plain files, in a folder on the user's own computer, owned by the user. Teach one AI something, and all of them know it. Local-first, works offline, bilingual (English + Arabic). Free core forever; early access opens 4 August 2026.

Callosium is a local-first memory layer for AI assistants (ChatGPT, Claude, Cursor, and any MCP-compatible client). The user's knowledge is stored as plain Markdown files with YAML frontmatter in a folder they own. Key differentiators: per-agent folder-scoped access (each AI only sees the folders it is granted, enforced structurally), server-stamped write attribution (every change is signed with who made it: the human, or which specific AI), deterministic offline recall (96.4% on a fresh 15,000-question benchmark, English and Arabic at parity, ~49ms typical and 116ms worst case, zero API keys required), and an honest "not in your brain" answer instead of hallucination (zero fabricated answers across all 15,000 questions including 1,450 deliberate traps; refusal precision 95.4%). The core engine is open source (Apache-2.0) from launch day. Paid tiers only add convenience (multi-device sync through the user's own cloud); user data is never hosted by Callosium.

## Main

- [Callosium home](https://callosium.com/): what it is, how it works, proof, pricing, FAQ
- [How it works](https://callosium.com/#how): three steps: knowledge in a folder, AIs plug in, all of them remember
- [Trust and proof](https://callosium.com/#proof): benchmark receipts, security review, scoped access, attribution
- [Pricing](https://callosium.com/#pricing): free core forever; Connected tier ~$5/mo at launch (BYO-cloud sync)
- [FAQ](https://callosium.com/#faq): data location, supported AIs, Obsidian compatibility, Arabic support, open source

## Facts

- Product: Callosium, local-first shared memory for AI assistants
- Launch: early access 4 August 2026 at callosium.com
- Storage: plain Markdown + YAML files on the user's machine; works with existing Obsidian vaults as-is
- Privacy: free version never sends files anywhere; no account holds the data
- Languages: English and Arabic, tested to the same benchmark bar
- Builder: solo founder (Abdo), building in public at https://x.com/callosium