I built a local-first tab manager and gave it an MCP server so Claude can organize my tabs
My browser is a war crime I'm a designer and developer, and a hopeless tab hoarder. On a normal day I've got 70+ tabs open across a couple of windows, every favicon crushed into an unreadable sliver, and my "system" for finding anything is to just… open another tab. Bookmarks? A write-only graveyard I never revisit. I bounced between tab managers for a while. Toby was the one that stuck — until…
The author is a designer and developer who struggles with an abundance of open tabs, usually around 70+ across multiple windows. Traditional tab managers like Toby, which cap the number of saved tabs, are unsatisfactory for someone with such a large number of tabs. This led the author to build their own local-first tab manager called Mos Tab.
Mos Tab adheres to three non-negotiable principles: local-first (no account required), no limits on the free version, and a calm dashboard instead of a list of tabs. It overrides chrome://newtab and uses a normalized tree data model (Space → Collection → Section → Tab) stored in a Zustand store with persist middleware for offline functionality.
The app includes a live side panel for managing tabs and collections, a command palette for searching saved tabs, and optional cloud sync through a paid tier. The backend is a Cloudflare Worker + R2 storing one JSON blob per user, syncing via conditional PUT requests and a 3-way merge on client-side conflicts.
A unique feature is the ability to connect Claude or ChatGPT to Mos Tab via a remote MCP server, allowing the AI assistant to search, summarize, save new tabs, and create share links—all from the chat interface. The implementation is straightforward, using add-only functionality to prevent accidental data loss, and reads and writes follow the same 3-way merge process as manual edits. The author emphasizes that all AI-generated content goes through the same sync mechanism as user-generated content.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — it may contain errors, so check the original before relying on it.
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