At a glance
The philosophical difference
LangMem is the memory SDK for the LangGraph ecosystem. It stores embeddings in a vector index and hands the agent tools to write, search, and update its own memory at runtime. Memory is self-managed: the model decides what is worth keeping. Worlds is storage-side. Facts enter through import and patches, relationships are explicit, and the ledger preserves the history of every change. Agents can write new facts through the update API, and each write lands in the append-only ledger as a verifiable patch (update). The difference is custody. LangMem trusts the model to curate its memory; Worlds curates at the data layer.When Worlds fits
- Facts must survive outside a single framework or agent lifetime.
- Answers need to be verifiable rather than similar.
- You want the same knowledge queryable from more than one framework.
When Worlds does not fit
- You want memory that lives inside your LangGraph application with no separate graph backend to configure.
- You want the model to decide what memory is worth keeping, with no ledger and no data-layer custody.
- Embeddings-only recall meets your requirements.