Compare frameworks
Letta vs Mastra vs Semantic Kernel
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 | Letta | Mastra | Semantic Kernel |
|---|---|---|---|
| Stars | 24,864Synced from sourceCurrent2h ago | 28,295Synced from sourceCurrent2h ago | 28,593 (highest of the compared values)Synced from sourceCurrent2h ago |
| downloads | — | 1,161,907Synced from sourceCurrent2h ago | — |
| Last commit | 2026-09-10Synced from sourceCurrent2h ago | 2026-09-24Synced from sourceCurrent2h ago | 2026-09-19Synced from sourceCurrent2h ago |
| Language | pythonSeeded, unreviewedwritten 1mo ago | typescriptSeeded, unreviewedwritten 1mo ago | csharpSeeded, unreviewedwritten 1mo ago |
| Licence | Apache-2.0Synced from sourceCurrent2h ago | — | MITSynced from sourceCurrent2h ago |
| Archived | noSynced from sourceCurrent2h ago | noSynced from sourceCurrent2h ago | noSynced from sourceCurrent2h ago |
| Category | memorySeeded, unreviewedwritten 1mo ago | orchestrationSeeded, unreviewedwritten 1mo ago | orchestrationSeeded, unreviewedwritten 1mo ago |
| Contributors | 155Synced from sourceCurrent2h ago | 678Synced from sourceCurrent2h ago | 416Synced from sourceCurrent2h ago |
| Forks | 2628Synced from sourceCurrent2h ago | 2845Synced from sourceCurrent2h ago | 4787Synced from sourceCurrent2h ago |
| Maintainer | LettaSeeded, unreviewedwritten 1mo ago | MastraSeeded, unreviewedwritten 1mo ago | MicrosoftSeeded, unreviewedwritten 1mo ago |
| npm downloads, monthly | — | 5528725Synced from sourceCurrent2h ago | — |
| npm downloads, weekly | — | 1161907Synced from sourceCurrent2h ago | — |
| npm package | — | @mastra/coreSynced from sourceCurrent2h ago | — |
| npm window ends | — | 2026-09-21Synced from sourceCurrent2h ago | — |
| Open issues | 0Synced from sourceCurrent2h ago | 447Synced from sourceCurrent2h ago | 320Synced from sourceCurrent2h ago |
| PyPI package | lettaSynced from sourceCurrent2h ago | — | semantic-kernelSynced from sourceCurrent2h ago |
| PyPI released | 2026-09-23T23:59:05.225455ZSynced from sourceCurrent2h ago | — | 2026-08-06T09:56:42.518861ZSynced from sourceCurrent2h ago |
| Requires Python | >=3.9Synced from sourceCurrent2h ago | — | >=3.10Synced from sourceCurrent2h ago |
| PyPI version | 0.33.0Synced from sourceCurrent2h ago | — | 1.44.1Synced from sourceCurrent2h ago |
| Repository | https://github.com/letta-ai/lettaSynced from sourceCurrent2h ago | https://github.com/mastra-ai/mastraSynced from sourceCurrent2h ago | https://github.com/microsoft/semantic-kernelSynced from sourceCurrent2h ago |
Sources: GitHub REST API, npm registry downloads, PyPI registry metadata, pypistats.org downloads. Most recent observation 2h 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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