Letta
a stateful-memory agent server (ex-memgpt)
a genuinely useful, narrow tool: a long-lived agent server with tiered memory persisted in postgres. the best persistent-memory model here, but opinionated and server-centric.
letta (the productised memgpt) runs agents as a long-lived server with tiered memory — a core context plus archival vector memory persisted in postgres — so agents accumulate and recall memory across sessions. you interact via a rest api and sdks, and it runs managed or self-hosted. for memory-centric use cases it's best-in-class and genuinely distinctive.
the trade-off is that it's an opinionated, server-centric architecture rather than a general orchestration framework, so it's narrower than most of this list. it's cross-provider. reach for it when persistent memory is the actual problem you're solving.
the description above is ours, condensed from the ranking. pricing moves — check it on the vendor's own page before you rely on it.
- category
- ai agent frameworks
- pricing
- free — Apache-2.0 (open source)
- website
- github.com
a genuinely useful, narrow tool: a long-lived agent server with tiered memory persisted in postgres. the best persistent-memory model here, but opinionated and server-centric.
we researched this category against vendors' own pricing pages and licence files. that is where this line comes from — not from the vendor, and not from anything they paid for.