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The best MCP knowledge base

A clear, honest comparison of the leading MCP knowledge bases and MCP note apps for giving ChatGPT and Claude a memory.

Last reviewed June 2026

Short answer

There is no single best MCP knowledge base; the right one depends on what you need. Hjarni is the pick if you want a hosted Markdown knowledge base both ChatGPT and Claude read and write. For an open-source memory layer for coding agents, mem0 or MemCP; for visual research, Heptabase; for spaced-repetition study, RemNote.

How to compare them

Five things matter for AI memory: a built-in MCP server (not a plugin to maintain), read and write (your AI keeps notes current, not just reads them), plain Markdown you own and can export, whether the same notes work with both ChatGPT and Claude, and hosted vs self-hosted reach. No tool wins on every axis, so the table below gives each one a fair "best for" rather than a single winner.

Comparison of MCP knowledge bases on what each is best for, MCP access, hosting, and the main tradeoff.
Tool Best for MCP access Main tradeoff
Hjarni Cross-assistant memory: a hosted Markdown knowledge base both ChatGPT and Claude read and write Built in, hosted (OAuth) Text-first notes, not a workspace or a whiteboard.
Notion Best if you also want a full workspace with databases and project management Built in, tied to Notion AI Powerful, but heavy if you only want AI-readable memory.
Obsidian Best local-first Markdown vault Third-party plugins Great files and plugins; AI access needs setup.
Heptabase Best for visual, whiteboard-style research and synthesis MCP integration (cards, whiteboards) Spatial thinking, less of a text-first memory layer.
RemNote Best for studying with spaced repetition Community MCP bridge Flashcard-first; the MCP bridge is unofficial.
Novi Notes Best local, Mac-only note app for desktop AI clients Local MCP (zero config) Local only: no remote clients like ChatGPT on the web.
AI Context Flow Best portable context layer across multiple AI tools MCP server + browser extension A context layer over other tools, not a full notes app.
mem0 / OpenMemory Best open-source memory layer for developers and agents OpenMemory MCP (local) An SDK and memory API, not a notes app you write in.
MemCP Best self-hosted memory graph for coding agents MCP server (local SSE or stdio) A developer tool: a temporal knowledge graph, no human notes UI.

How the category breaks down

The field splits into three shapes. Workspaces and note apps with MCP bolted on (Notion, Obsidian, Heptabase, RemNote). Developer memory layers you wire into your own code (mem0, MemCP). And knowledge bases built around MCP from the start, like Hjarni, where the MCP server is built in, the notes are plain Markdown you read and write as a human, and the same notes work with both ChatGPT and Claude from any device. Which group fits depends on whether you are writing notes yourself or wiring memory into an agent.

The honest caveats matter. If you also need databases and project management, Notion is the better product. If you must keep files on your own machine, Obsidian, or a self-hosted option like Khoj, fits better. If you are a developer adding memory to an agent rather than writing notes yourself, mem0 or MemCP are the right tools. And local-only apps like Novi Notes are great on a single Mac but cannot serve ChatGPT on the web, because there is no hosted endpoint for a remote client to reach.

Pick by what you actually need

Choose Hjarni

You want one durable, hosted knowledge base that ChatGPT, Claude, and other MCP clients read and write, in plain Markdown you own.

Choose Notion

You also want databases, project management, and a company wiki, and you are happy with AI tied to Notion AI.

Choose Obsidian

Local files and a plugin ecosystem matter most, and you will set up AI access yourself.

Choose Heptabase or RemNote

You want visual whiteboard thinking, or spaced-repetition study, with AI as a bonus.

Choose mem0 or MemCP

You are a developer adding a memory layer to an agent or coding workflow, not writing notes by hand.

Choose Novi Notes

You want a cheap, local, Mac-only note app for desktop AI clients and never need a remote one.

The best MCP knowledge base is the one every AI you use can read.

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Common questions

Questions about choosing an MCP knowledge base

What is the best MCP knowledge base?

It depends on what you need. For people who use more than one AI and want a hosted, writable Markdown knowledge base, Hjarni is a strong pick: ChatGPT, Claude, and other MCP clients read and write the same notes. For an open-source memory layer for coding agents, mem0 or MemCP. For visual research, Heptabase. For spaced-repetition study, RemNote.

What is an MCP knowledge base?

A knowledge base your AI connects to over the Model Context Protocol. Instead of pasting context into the chat, the assistant reads and writes your notes directly. The best ones speak plain Markdown and work with every MCP client, not just one.

Which MCP knowledge bases work with both ChatGPT and Claude?

Hosted ones with a remote MCP endpoint. Hjarni works with ChatGPT and Claude from any device. Local-only tools like Novi Notes or Bear can reach desktop clients such as Claude Desktop, but not ChatGPT on the web, because there is no hosted endpoint for a remote client to call.

Is mem0 a knowledge base?

Not in the notes-app sense. mem0 is an open-source memory layer and SDK for AI agents, plus the OpenMemory MCP server. It is excellent for developers adding memory to an application. Hjarni is the notes app a person writes in and an assistant reads, with the MCP server built in.

What is the best free MCP knowledge base?

Hjarni's free tier includes full MCP access with no token limits (25 notes). Several developer-focused options are open-source and free to self-host, including mem0 OpenMemory and MemCP, though you run and maintain those yourself.

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