Compare frameworks
Pydantic AI vs LangGraph vs Letta
Every figure below carries the source that reported it and the moment it was observed. Values that failed validation are withheld rather than shown, and a dash means no source we track carries that field for that framework.
| Field | Pydantic AI | LangGraph | Letta |
|---|---|---|---|
| Stars | 20,220Synced from sourceCurrent4h ago | 42,384 (highest of the compared values)Synced from sourceCurrent4h ago | 24,923Synced from sourceCurrent4h ago |
| downloads | 3,076,771Synced from sourceStale1mo ago· past SLA | 3,773,725 (highest of the compared values)Synced from sourceCurrent4h ago | — |
| Last commit | 2026-09-28Synced from sourceCurrent4h ago | 2026-09-27Synced from sourceCurrent4h ago | 2026-09-10Synced from sourceCurrent4h ago |
| Language | pythonSeeded, unreviewedwritten 1mo ago | pythonSeeded, unreviewedwritten 1mo ago | pythonSeeded, unreviewedwritten 1mo ago |
| Licence | MITSynced from sourceCurrent4h ago | MITSynced from sourceCurrent4h ago | Apache-2.0Synced from sourceCurrent4h ago |
| Archived | noSynced from sourceCurrent4h ago | noSynced from sourceCurrent4h ago | noSynced from sourceCurrent4h ago |
| Category | structured-outputSeeded, unreviewedwritten 1mo ago | orchestrationSeeded, unreviewedwritten 1mo ago | memorySeeded, unreviewedwritten 1mo ago |
| Contributors | 609Synced from sourceCurrent4h ago | 287Synced from sourceCurrent4h ago | 155Synced from sourceCurrent4h ago |
| Forks | 2796Synced from sourceCurrent4h ago | 7174Synced from sourceCurrent4h ago | 2631Synced from sourceCurrent4h ago |
| Maintainer | PydanticSeeded, unreviewedwritten 1mo ago | LangChainSeeded, unreviewedwritten 1mo ago | LettaSeeded, unreviewedwritten 1mo ago |
| npm downloads, monthly | — | 12375862Synced from sourceCurrent4h ago | — |
| npm downloads, weekly | — | 3773725Synced from sourceCurrent4h ago | — |
| npm package | — | @langchain/langgraphSynced from sourceCurrent4h ago | — |
| npm window ends | — | 2026-09-26Synced from sourceCurrent4h ago | — |
| Open issues | 1013Synced from sourceCurrent4h ago | 831Synced from sourceCurrent4h ago | 0Synced from sourceCurrent4h ago |
| PyPI downloads, monthly | 13478631Synced from sourceStale1mo ago· past SLA | — | — |
| PyPI downloads, weekly | 3076771Synced from sourceStale1mo ago· past SLA | — | — |
| PyPI package | pydantic-aiSynced from sourceCurrent4h ago | langgraphSynced from sourceCurrent4h ago | lettaSynced from sourceCurrent4h ago |
| PyPI released | 2026-09-25T23:32:17.554286ZSynced from sourceCurrent4h ago | 2026-09-21T14:43:28.196799ZSynced from sourceCurrent4h ago | 2026-09-28T04:32:31.896015ZSynced from sourceCurrent4h ago |
| Requires Python | >=3.10Synced from sourceCurrent4h ago | >=3.10Synced from sourceCurrent4h ago | >=3.9Synced from sourceCurrent4h ago |
| PyPI version | 2.51.0Synced from sourceCurrent4h ago | 1.2.12Synced from sourceCurrent4h ago | 0.33.5Synced from sourceCurrent4h ago |
| Repository | https://github.com/pydantic/pydantic-aiSynced from sourceCurrent4h ago | https://github.com/langchain-ai/langgraphSynced from sourceCurrent4h ago | https://github.com/letta-ai/lettaSynced from sourceCurrent4h ago |
Sources: GitHub REST API, npm registry downloads, PyPI registry metadata, pypistats.org downloads. Most recent observation 4h ago. Where a row is marked, ▲ is the highest of the values shown and ▼ the lowest — arithmetic on the figures above, not a ranking or a recommendation. Rows where neither extreme is meaningful are left unmarked rather than given a direction they do not have.
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