Letta vs Mem0
| Mem0 | Letta | |
|---|---|---|
| Storage | Vector + graph | Hierarchical (core / archival) |
| Authorship | Auto-extract | Auto-extract + manual edit |
| Hosted | Yes | Yes + self-host |
| Format | JSON memories | Block-based |
| OSS | Yes | Yes (formerly MemGPT) |
Where they differ
Letta inherits MemGPT's "context windows are an OS resource" framing — core memory (always loaded) vs archival (paged in). Mem0 is flatter: all memories are vectors, top-K retrieved per turn.
Where they're similar
Both treat memory as something the system extracts from the user's behavior. Neither makes memory addressable as a URL the user can paste into a different AI.