Mem0 vs Zep vs Letta AI coding memory: what it is and which to pick
Mem0 vs Zep vs Letta AI coding memory is the comparison between three well-known agent memory projects and the narrower job of remembering your decisions across coding tools such as Claude Code, Cursor and Codex. Short answer: Mem0, Zep and Letta are built for agents you ship, while developers using several coding tools need memory that works across those tools and stays on their own machine.
We make one of the options, so weigh this accordingly. At Open Agentic Brain & Memory (OpenAB), we build free, open-source (Apache-2.0), self-hosted memory for AI coding tools. Below we say where the others are the better choice, and there are several such cases.
One note on sourcing. We did not run benchmarks on Mem0, Zep or Letta, so we give no star counts or speed figures for them. Their descriptions below reflect how each project presents itself, and you should confirm licences and hosting terms in each project's own docs before committing. The OpenAB numbers are our own, from our own benchmark runs.
What you need from memory when you use more than one coding tool
The problem is simple. You decide on Monday, in Claude Code, to drop Redis and use SQLite. On Tuesday you open Cursor, and it suggests Redis. You explain it all again. Every session starts from zero, and no tool knows what the others learned.
Four requirements follow from that:
Cross-tool reach. One memory that several tools read from and write to, not one store per tool.
Automatic capture. If you must maintain notes by hand, you will stop doing it within a week.
Bounded context. Memory that dumps everything into the prompt burns your token limits.
Clear ownership. You should be able to answer "where does my memory live, and who can read it?"
Most memory projects were designed for a different job: giving an agent inside your product a memory of its users. That is a good job, but it is not this one.
Mem0 vs Zep vs Letta for AI coding memory: which should you choose?
The three are not interchangeable, and none of them targets "one memory across my coding tools" as its main use case. Each gets its own section below, followed by a table.
Mem0
Mem0 is a memory layer you add to an AI application. It extracts facts from conversations, stores them, and retrieves them later through an API. It offers both an open-source library and a hosted service. It fits when you are building a chatbot or assistant and want it to remember each end user. For coding tools you would be writing the capture and injection glue yourself, per tool. If you use the hosted service, your memory sits on their servers, so check their data terms.
Zep
Zep stores agent memory as a temporal knowledge graph, which tracks how facts change over time. Its open-source graph library is called Graphiti. That design suits agents dealing with changing business data, such as a customer whose plan or address changes. It is more machinery than a solo developer needs to remember "we use pnpm". Zep is also aimed at production agent deployments, not at a developer's editor sessions, and it does not come wired into coding tools out of the box.
Letta
Letta began as MemGPT, a research project on letting a model manage its own memory. It is now an agent framework: the agent, its memory and its state all live inside Letta's runtime. That makes it a memory layer only in a loose sense. If you want a stateful agent built on Letta, it is a strong choice. If you want Cursor and Claude Code to share what they learned, you would be adopting a whole framework to get there.
Claude-mem and other single-tool plugins
Plugins like Claude-mem add session memory to one tool, usually Claude Code. They are quick to install and good at what they do. The limit is in the name: the memory lives with that tool. Open Cursor and it knows nothing. For a developer who only ever uses one tool on one machine, this is often enough, and you should not add complexity you do not need.
OpenAB
OpenAB is one memory shared across Claude Code, Cursor, Codex, Antigravity and Kilo Code (beta). It captures decisions, fixes and preferences from your sessions, tags them by project (found by walking up to the nearest .git), and stores them in a local SQLite database. At session start a hook injects a briefing of at most 2,000 tokens, in 84 ms (p50). Tools can also recall on demand over MCP, in 28 ms (p50) across 10,000 memories. You can see how it works on the OpenAB site.
Single-tool plugins, hosted APIs, graph memory and agent frameworks compared
OptionWhat it storesWhere data livesCross-tool coding supportAutomatic captureLicence
Mem0Extracted facts about users and sessionsYour infrastructure (open source) or Mem0's hosted serviceNot built in; you integrate itYes, inside your app's codeOpen-source library plus hosted service; confirm in docs
Zep / GraphitiTemporal knowledge graph of factsHosted service, or self-run GraphitiNot built inYes, from messages you send itGraphiti open source; confirm Zep's terms in docs
LettaAgent state and memory blocksLetta runtime, self-hosted or hostedNot its purpose; the agent lives in LettaAgent-managedOpen source; confirm in docs
Single-tool plugins (e.g. Claude-mem)Session notes for one toolLocal, per toolOne toolYesVaries by plugin
OpenABDecisions, fixes and preferences, tagged by projectLocal SQLite; synced as an age-encrypted blob in your own private GitHub repoClaude Code, Cursor, Codex, Antigravity, Kilo Code (beta)Yes, through hooksApache-2.0
Where a cell says "confirm in docs", that is deliberate. Licences and hosting terms change, and we would rather send you to the source than state something stale.
Where each one stores data and who can read it
This is the question that separates the options most sharply, and it is where we have the clearest opinion.
With a hosted API, your memory sits on the vendor's servers. For a coding tool that can include architecture decisions, internal service names and the reason you rejected a vendor. Reputable providers publish their security terms, and you should read them. But "we protect it" and "we never hold it" are different claims.
OpenAB takes the second route. There is no account and no server of ours. Memory lives in local SQLite. To sync between laptops, it is age-encrypted, with the key kept only in the OS Keychain, and uploaded as a Release asset in your own private GitHub repo. A leaked repo or token exposes nothing readable. The flip side is real: only you hold the key, and if you lose it, nobody can recover your memory.
You can also read, edit, pin or delete every memory from a local control panel. That matters more than it sounds. Memory you cannot inspect is memory you cannot trust.
Saving tokens is part of the comparison
Memory that gets pasted into every prompt costs you limits. In our benchmark, loading context for a 10,000-memory store takes 1,325 tokens through OpenAB, against 1,131,367 for the full text. On LoCoMo, a public long-conversation benchmark, it keeps 97% of the full-conversation score while reading 18% of the tokens. These are our own measurements, so run brain eval on your own history and see what you get. Fewer tokens per session means you reach Claude, Cursor or Codex limits later.
When OpenAB is the right fit, and when another option is
Pick OpenAB if you switch between coding tools or machines, you are tired of re-explaining projects, and you want the data to stay yours. It is free, so the cost of trying it is an afternoon. Details and install steps are on the OpenAB project page.
Pick something else in these cases:
You are building a product that remembers its end users: Mem0 or Zep.
You want a stateful agent runtime with memory built in: Letta.
You use exactly one tool on one machine: a single-tool plugin, or just a CLAUDE.md file.
You want a hosted service with no setup. OpenAB has no hosted option, and our brand is younger with less community proof than these projects. Kilo Code support is still beta.
For Mem0 vs Zep vs Letta AI coding memory specifically, our view is this: they are strong at what they were built for, and that is agents you ship. For the daily reality of one developer and several coding tools, you want capture through hooks, a small bounded briefing, and data you hold the key to.
Frequently asked questions
Is OpenAB a replacement for Mem0 or Zep?
No. Mem0 and Zep are memory layers for applications you build, usually serving many end users. OpenAB is memory for your own coding sessions across tools. You could reasonably use OpenAB for your editor and Mem0 or Zep inside a product you ship.
Which AI coding tools can share one OpenAB memory today?
Claude Code, Cursor, Codex and Antigravity share one memory, and Kilo Code works in beta. Claude Desktop and ChatGPT desktop also appear on the site's integrations strip. Check the OpenAB site for the current list before installing.
Can I use Mem0 for AI coding memory?
You can, but you would build the capture and injection for each coding tool yourself. Mem0 is designed as a memory layer inside an application. It does not ship as a ready-made memory for editors.
Is Letta a memory layer or an agent framework?
Mostly an agent framework. It grew out of MemGPT, and its memory is part of a stateful agent running in Letta's runtime. That works well if you build agents on Letta, but it is not a drop-in memory for Cursor or Claude Code.
Does Zep work across Claude Code and Cursor?
Zep is a knowledge-graph memory service you integrate through its API, so cross-tool use means writing that integration. It is not packaged for coding tools. Check Zep's docs for current integrations.
What is the best memory for using several AI coding tools?
One that works across tools, captures automatically, and keeps data under your control. That is the case OpenAB is built for. If you only use one tool, a single-tool plugin may be all you need.
Where is my coding data stored with OpenAB?
In a local SQLite database on your machine. For cross-machine sync it is age-encrypted and stored as a Release asset in your own private GitHub repo, with the key held only in your OS Keychain. There is no account and no OpenAB server.
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