Mem0 vs Zep vs Letta vs Verbasil: memory building block or company memory
These four names come up together in searches, and that is misleading. Three of them are building blocks developers assemble. The fourth is a product you open and use.
That is not a positioning nuance. It is the only question that decides: is somebody at your company going to write code, or not?
Let us be clear right away: on the memory model itself, Zep is more sophisticated than most people assume, and on some points it does what Verbasil does. The table below says so. What separates them is elsewhere.
Each line is dated and links to the public repositories. If any of it has changed since, write to us and we will correct the page.
The table
Recorded on 4 August 2026.
| Mem0 | Zep | Letta | Verbasil | |
|---|---|---|---|---|
| Usable without writing code | ❌ pip or npm library | ❌ Python, TypeScript, Go SDKs | ❌ CLI and SDK | ✅ You open it and use it |
| Interface for a non-developer | ❌ | ❌ | 🟡 CLI, desktop app announced | ✅ |
| Validity windows on facts | 🟡 | ✅ Bi-temporal through Graphiti | 🟡 | ✅ |
| Provenance back to the source | 🟡 | ✅ Every fact tied to its source episode | 🟡 | ✅ |
| Surface a recurrence to a human | ❌ Served to an agent, not to a person | ❌ | ❌ | ✅ Daily briefing of what matters |
| Decision, experiment, learning cycle | ❌ | ❌ | ❌ | ✅ Built into the product |
| Open source | ✅ Apache 2.0 | 🟡 Apache 2.0 but community edition deprecated | ✅ Apache 2.0 | ❌ |
| Self-hosting | ✅ docker compose up | ❌ No longer maintained, managed offering only | ✅ Local or self-hosted server | ❌ |
| Technical control and customisation | ✅ | ✅ Entity types defined in Pydantic | ✅ Model-agnostic | 🟡 Closed product |
| Guaranteed hosting in Europe | 🟡 Depends on your deployment | 🟡 | 🟡 Depends on your deployment | ✅ |
| Plugged into consumer AI assistants | 🟡 To be integrated | 🟡 To be integrated | 🟡 To be integrated | ✅ MCP server, immediate |
Four lines go to the building blocks, and they matter. Open source, self-hosting and technical control: if you want to read the code, modify it, host it yourself and pay infrastructure cost, Mem0 and Letta do what Verbasil does not. Verbasil is a closed, hosted product.
And on the temporal model, Zep owes us nothing. Graphiti gives every fact a validity window, automatically invalidates contradicted facts without deleting them, keeps the full history and lets you query the state of knowledge at any point in time (Graphiti, accessed 04/08/2026). That is exactly the right way to model knowledge that changes, and they do it very well.
So what actually separates us?
One thing, and it decides everything: who does the work.
Mem0 installs with pip install mem0ai and is used by writing code (Mem0 repository, accessed 04/08/2026). Zep is consumed through Python, TypeScript or Go SDKs (Zep repository, accessed 04/08/2026). Letta runs from the command line or through its SDK, with no traditional interface (Letta repository, accessed 04/08/2026).
These are excellent engines. You are missing the car around them.
For one of those blocks to become your company memory, you need to: decide what to send it, write the ingestion from your emails and meetings, build an interface, define what a decision means at your company, write the logic that surfaces what matters, handle permissions, and maintain all of it. That is a product. That is several months of a developer.
If you have that developer and this memory is your product, take a building block. Genuinely: they are good, they are open, and you keep control.
If you are a founder and your product is something else, you are not going to build this. And that is exactly why Verbasil exists.
Three differences that are not technical
The memory is returned to a human, not to an agent. Mem0, Zep and Letta serve context to a model at the moment it answers. That is their job and they do it well. Verbasil speaks to you first: a daily briefing of what the memory retained, what deserves attention, the next decision to settle. A building block has nobody to warn.
The vocabulary is a company's, not a graph's. Verbasil handles decisions, experiments, learnings, customer feedback, decision debt. These objects have a lifecycle: a decision becomes an experiment, which produces a result, which becomes a learning. With a building block, that model is yours to design and code.
Hosting is decided, not configurable. Your data is in Europe, full stop. With a self-hosted block it is your choice and your responsibility; with a managed offering it depends on theirs.
When to pick a building block over Verbasil
Plainly, here are the cases where you should not take us.
- You are building a product whose core is memory. Take Mem0 or Letta, keep control of the engine.
- You must self-host, for regulatory or internal policy reasons. Verbasil is hosted, with no self-hosting option.
- You need to model your own entity types. Zep lets you define them in Pydantic, Verbasil does not.
- You want to read and modify the code. Our competitors here are Apache 2.0, we are not.
In all of those cases they are the better choice, and a comparison claiming otherwise would not be doing you a favour.
When to take Verbasil
- You are a founder or in a small team, and nobody is writing the email ingestion this quarter.
- You want the memory to speak to you first, not to answer an agent you must build yourself.
- You think in decisions, customer feedback and learnings, not in nodes and edges.
- You want to plug ChatGPT, Claude or Cursor into your memory today, without writing an integration (your company's memory shouldn't live inside any AI).
Book a memory audit: free, 30 minutes, we look together at what your company has already forgotten.
FAQ
Is Verbasil a competitor to Mem0, Zep and Letta?
Not really. They are memory building blocks for developers, shipped as libraries and SDKs. Verbasil is the finished product for a founder or a small team. We show up in the same searches because we all talk about memory, but we do not address the same people.
Doesn't Zep already do temporal validity on facts?
Yes, and very well. Graphiti, which powers Zep, gives every fact a validity window, automatically invalidates contradicted facts without deleting them, and lets you query the state of knowledge at any point in time. On that specific point there is no gap in our favour. The difference is that you have to build a product around it, where Verbasil is one.
Can I use Mem0 or Letta instead of Verbasil?
Yes, if you have a developer and you accept building the ingestion, the interface, the decision model and the retrieval. That is several months of work. If your product is the memory, it is the right investment. Otherwise it is a detour.
Is Verbasil open source?
No. Mem0 and Letta are Apache 2.0, and Zep's community edition is deprecated in favour of their managed offering. If reading and modifying the code is a criterion, they are better choices than us.
Can Verbasil be self-hosted?
No. Your data is hosted in Europe and is exportable, but there is no self-hosting option. Mem0 and Letta offer one.