One knowledge base for ChatGPT and Claude

Short answer

Hjarni is a hosted knowledge base with a built-in MCP server, so the same notes are readable and writable by both ChatGPT and Claude. Connect each once and they share one memory, instead of each assistant keeping its own siloed context.

Why single-assistant memory is not enough

ChatGPT memory lives inside ChatGPT. Claude Projects live inside Claude. Each is useful, but neither can read the other, so the moment you switch tools you are re-explaining yourself again. If you use both, what you actually want is one knowledge base they both read from and write to.

How one shared knowledge base works

Hjarni stores your notes as plain Markdown and exposes them through a built-in MCP server. You connect ChatGPT once and Claude once. From then on both read the same notes, and either can write back. Update a note in Claude and it is what ChatGPT reads next. There is one source of truth, not two memories drifting apart.

ChatGPT

Add Hjarni as an MCP connector. Two minutes.

Set up ChatGPT

Claude

Add Hjarni as a connector. Two minutes.

Set up Claude

One account, every assistant

You bring whichever assistants you already pay for; Hjarni does not bundle or charge for the AI itself. The same notes also work with Cursor, Claude Code, and GitHub Copilot, and Gemini will work once it supports MCP, with no change on your side. See every integration.

Stop keeping one memory in ChatGPT and another in Claude. Keep one, and let both read it.

Give your AI a memory

Common questions

Questions about one knowledge base for both

Is there a knowledge base that works with both ChatGPT and Claude?

Yes. Hjarni is a hosted knowledge base with a built-in MCP server, so the exact same notes are readable and writable by both ChatGPT and Claude. You connect each one once, and they share the same memory.

Why not just use ChatGPT memory or Claude Projects?

Each lives inside one assistant. ChatGPT memory only helps ChatGPT; Claude Projects only helps Claude. A shared knowledge base over MCP gives both assistants the same notes, so you stop re-explaining context when you switch tools.

Do I need separate accounts or subscriptions?

One Hjarni account works with every MCP client. You bring whichever assistants you already use; Hjarni does not bundle or charge for the AI itself.

Does a note stay in sync across ChatGPT and Claude?

Yes. Notes live in Hjarni, not inside either assistant. An update Claude makes is what ChatGPT reads next, and vice versa. There is one source of truth.

What about Gemini, Cursor, or Copilot?

Any MCP-capable client connects to the same notes, including Cursor, Claude Code, and GitHub Copilot. Gemini will work once it supports MCP, with no change on your side.

Give your AI a memory

Write once. You both remember.

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Give your AI a memory

Works with Claude and ChatGPT today. Gemini coming soon.