Best MCP Memory Servers in 2026: 7 Options Compared

If you want a hosted Markdown knowledge base ChatGPT and Claude can both read and write, Hjarni is a strong fit. Supermemory offers managed memory across connected sources for personal, shared, and application use. For memory inside an agent product, also consider Mem0 or Graphiti. For local Markdown files with an optional cloud service, consider Basic Memory. Letta belongs in the comparison as an agent platform, rather than a drop-in memory server.

The short version

Option	Best for	MCP connection	Main tradeoff
Hjarni	Shared, editable notes across assistants	Hosted server	Focused knowledge base; no offline mode
Mem0 / OpenMemory	Application memory and coding agents	OpenMemory MCP	Distinguish the MCP product from the Mem0 API
Supermemory	Managed memory and connected sources	Hosted MCP	Check the MCP plan separately from API usage
Zep / Graphiti	Context that changes over time	Graphiti MCP server	You operate the graph infrastructure when self-hosting
Letta	Building agents with persistent memory	Agents connect to external MCP servers	An agent platform, not an interchangeable memory endpoint
Basic Memory	Markdown files, locally or in the cloud	Local and hosted MCP	Remote access and sync depend on the chosen setup
Reference knowledge graph server	Learning how MCP memory works	Local MCP	Basic graph storage rather than a shared notes application

How I picked

I am Evert, the founder of Hjarni. This is my assessment of the documented products, not an independent ranking or a hands-on benchmark. I compared what stores the memory, who can edit it, how an assistant reaches it, who operates it, and the cost model. The order reflects use cases, not measured performance.

Sources checked September 17, 2026. Each entry links to vendor documentation or the project's own repository. Follow the pricing links for current allowances and billing terms. A local MCP server needs a local-capable client or a separately configured bridge; a hosted endpoint still needs a compatible client and permission to connect.

1. Hjarni

Hjarni stores Markdown notes in folders with tags. ChatGPT and Claude can search, read, create, and update those notes through the built-in MCP server. You can inspect the notes yourself and review or revert edits.

Choose it when you want one editable knowledge base across assistants, or shared folders for a small team. Folder instructions carry your conventions when the assistant fetches them.

Choose something else when you need offline files or a memory API embedded in your own product. Hjarni does not automatically ingest every conversation. Ask your assistant to search before answering and save decisions back. See how to make that a habit.

Cost: free to start, with paid personal and team plans. Current Hjarni pricing.

2. Mem0 / OpenMemory

Mem0 provides memory infrastructure for AI applications. OpenMemory provides an MCP interface for coding-agent memory. Treat the Mem0 API and OpenMemory as related products with their own setup and billing choices. OpenMemory overview, local OpenMemory introduction.

Choose it when you are building an application that retrieves stored facts, or want memory in a coding workflow.

Check first: whether you need the local OpenMemory implementation, its managed offering, or the Mem0 API. Do not assume one product's allowances apply to another. Mem0 pricing.

3. Supermemory

Supermemory offers a memory API, connected content sources, and a hosted MCP endpoint with OAuth. Its MCP product also supports shared spaces. It is an option for people connecting existing assistants as well as developers building applications. Product and MCP overview.

Choose it when managed ingestion and retrieval across connected sources matter more than maintaining a folder tree of authored Markdown notes.

Check first: the distinction between API usage and the MCP offering. Compare the relevant allowance and overage model with your workload. Supermemory pricing.

4. Zep / Graphiti

Graphiti is Zep's open-source framework for a graph that tracks relationships and changes over time. Its repository includes an MCP server with tools for episodes, entities, relationships, and search. Graphiti documentation and MCP server.

Choose it when you are building agents that need structured relationships and changing state.

Check first: the database and model requirements for self-hosting. Graphiti's open-source code and Zep's managed service are different deployment choices. This is infrastructure you integrate, rather than a ready-made writing application.

5. Letta

Letta is an agent platform. Its documented MCP integration connects Letta agents to external tool servers. That is a different role from a server you add to ChatGPT so it can search your notes. Letta MCP documentation.

Choose it when you want to build an agent and its memory workflow within a platform.

Choose another option here when you only need an external knowledge base for an assistant you already use. Confirm the integration direction before treating any product's “MCP support” as a memory endpoint.

6. Basic Memory

Basic Memory uses Markdown files for memory. It offers both a local setup and Basic Memory Cloud. Cloud includes a remote MCP connection and a web editor, so it should not be described as desktop-only. Basic Memory Cloud guide.

Choose it when local Markdown ownership matters, or you want the option to move to hosted access.

Check first: how you want local files and cloud projects to stay in sync. Local mode requires a reachable local server; Cloud solves a different access problem. Cloud setup and subscription.

7. The reference knowledge graph server

The Model Context Protocol project's memory server stores entities, relationships, and observations in a local graph. It includes search across entity names, types, and observations.

Choose it when you want a small, open-source reference implementation to understand MCP memory.

Choose something else when you need a hosted team knowledge base, an editor, or managed synchronization. Its basic search should not be confused with a full semantic retrieval service.

The best MCP memory server, by use case

• One knowledge base for ChatGPT and Claude: Hjarni, or Basic Memory Cloud if its file workflow suits you better. Compare MCP knowledge bases for workspace and study tools too.
• Shared business notes: Hjarni Teams. Everyone connects their own assistant and can retrieve the same shared notes.
• Memory inside your own AI product: Mem0 or Supermemory. Compare the API and deployment you would actually use.
• A graph that tracks changing relationships: Graphiti.
• An agent platform: Letta.
• Local Markdown files: Basic Memory.
• A reference implementation to learn from: the knowledge graph server.

For a closer comparison, read Mem0 vs Supermemory vs Hjarni. For agent workflows, see how to choose a knowledge base for AI agents.

For the wider choice between built-in memory, files, and external knowledge bases, read the best ways to give your AI memory.