LangMem vs Letta
A side-by-side comparison of LangMem and Letta, two Memory tools, drawn from Ignaite's continuously-verified listings.
Compared from listings verified as of
At a glance
| Attribute | LangMem | Letta |
|---|---|---|
| Category | Memory | Memory |
| Pricing (differs) | FREE | FREEMIUM |
| License (differs) | Open source | Open core |
| Deployment (differs) | — | Hybrid |
| Platforms (differs) | API, CLI | API, CLI, macOS, Windows, Linux |
| Model support | BYO key / model | BYO key / model |
| Vendor (differs) | LangChain | Letta |
The honest brief
LangMem
Backed by LangChain, its memory tools plug straight into LangGraph rather than running as a standalone store.
- Semantic, episodic, procedural memory
- Storage- and framework-agnostic core API
- Native LangGraph integration
- MIT-licensed and free
- Most value inside the LangChain stack
- Young SDK, evolving API
- You wire up your own storage layer
Letta
The productized MemGPT successor — agents edit their own memory blocks (memory-as-OS) to manage a finite context window.
- Self-editing agent memory
- Open source, model-agnostic
- REST APIs + multi-language SDKs
- Reference architecture for memory
- Developer-focused, not no-code
- Memory model has a learning curve
- Younger, evolving framework