# 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.

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.

We publish Hjarni. This comparison is based on the linked vendor docs and maintainer repositories, checked September 17, 2026. It is not a hands-on benchmark.

Compare five things: **who maintains the MCP server**, **read and write access**, **exportable Markdown**, **ChatGPT and Claude compatibility**, and **local or hosted access**. Pick the tradeoff that fits your work.

| Tool | Best for | MCP access | Main tradeoff |
| --- | --- | --- | --- |
| Hjarni | Shared, editable Markdown notes for ChatGPT and Claude | Built in, hosted (OAuth) [Source for Hjarni](https://hjarni.com/docs/mcp) | Focused knowledge base; no offline mode. |
| [Notion](https://hjarni.com/compare/hjarni-vs-notion) | Databases, documents, and project management together | Official hosted MCP [Source for Notion](https://www.notion.com/help/notion-mcp) | External assistants can read and write; choose it if you also need a workspace. |
| [Obsidian](https://hjarni.com/compare/hjarni-vs-obsidian) | A Markdown vault on your own disk | Third-party servers [Source for Obsidian](https://github.com/maxkuminov/obsidian-mcp) | You choose and maintain the MCP server; remote access depends on its deployment. |
| [Joplin](https://hjarni.com/compare/hjarni-vs-joplin) | Open-source notes with optional encrypted sync | Built in, local (3.7+) [Source for Joplin](https://joplinapp.org/help/apps/ai_mcp/) | Desktop MCP listens on localhost; web assistants need a bridge. |
| [Logseq](https://hjarni.com/compare/hjarni-vs-logseq) | Block-based outlines and journals | Community MCP server [Source for Logseq](https://github.com/dailydaniel/logseq-mcp) | The linked server needs Logseq running and its HTTP API enabled. |
| Heptabase | Visual research using cards and whiteboards | Official hosted MCP [Source for Heptabase](https://support.heptabase.com/en/articles/12679581-how-to-use-heptabase-mcp) | External assistants can read and edit content; the product centers on visual research. |
| RemNote | Study notes and spaced repetition | Built in, local desktop MCP [Source for RemNote](https://help.remnote.com/en/articles/16424066-connecting-ai-agents-to-remnote-with-mcp) | Web-only assistants cannot connect directly to the local server. |
| Basic Memory | Markdown memory with a local or cloud choice | Local and hosted MCP [Source for Basic Memory](https://docs.basicmemory.com/cloud/cloud-guide) | Local mode needs your machine; Cloud adds remote access and a web editor. |
| mem0 / OpenMemory | Memory for applications and coding agents | OpenMemory MCP [Source for mem0 / OpenMemory](https://mem0.ai/openmemory) | Check OpenMemory separately from Mem0 API plans; they serve different workflows. |
| MemCP | Persistent context for Claude Code | Self-hosted MCP server [Source for MemCP](https://github.com/maydali28/memcp) | The linked project stores insights in SQLite and context on disk; setup is yours. |

## How the category breaks down

The field splits into three shapes. Workspaces and note apps that offer AI access (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. Local servers such as Joplin's and RemNote's need a bridge for web-only assistants. Basic Memory offers both local and hosted options. Notion and Heptabase also offer hosted MCP access for external assistants.

## 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 your external AI assistant can read and write.

### 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 Basic Memory

You want Markdown files on your own disk, with a hosted option if you later need remote access.

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

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?**

Hjarni, Notion, Heptabase, and Basic Memory Cloud offer hosted MCP access for compatible ChatGPT and Claude clients. Local-only servers such as Joplin and RemNote need a local-capable client or a separately configured bridge. Check the client plan and connection requirements.

**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.

**What is the best MCP knowledge base for a small business?**

One your whole team and every assistant can share. With [Hjarni Teams](https://hjarni.com/for-teams), your positioning, customer notes, and decisions live in shared folders, and each person's own ChatGPT or Claude reads the same source of truth. Developer memory layers store extracted fragments, which is the wrong shape for business knowledge you need to read and correct.

## On every device. In every assistant.

Native apps for iPhone, iPad, Mac and Android, and official listings in both the ChatGPT and Claude directories. One account, one set of notes.

Web, any browser

[iPhone and iPad](https://apps.apple.com/app/id6761733903)

[Mac](https://apps.apple.com/app/id6761733903)

[Android](https://play.google.com/store/apps/details?id=com.hjarni.app)

[Chrome web clipper](https://chromewebstore.google.com/detail/hjarni-web-clipper/ooingmimhhkeohmkkkhpnlnhgefaaajb)

The apps are free, with the same features as the web.

[ChatGPT app](https://chatgpt.com/plugins/plugin_asdk_app_69c3058914bc81919b807c176a7c106c)

[Claude connector](https://claude.ai/directory/connectors/hjarni-notes)

[Cursor](https://hjarni.com/for/cursor)

[Claude Code](https://hjarni.com/for/claude-code)

[20+ MCP clients](https://hjarni.com/compatibility)

Hjarni is listed in the [ChatGPT Apps Directory](https://chatgpt.com/plugins/plugin_asdk_app_69c3058914bc81919b807c176a7c106c) and the [Claude Connectors Directory](https://claude.ai/directory/connectors/hjarni-notes), so connecting is an install, not a config file.

[How to get Hjarni on each one](https://hjarni.com/get)