Both are open source harness options with comparable terms, so the choice comes down to which model of the problem you prefer — compare the descriptions below rather than the licence.
Block's open-source on-machine agent with an extension system.
Stateful agent server where memory is the primary abstraction.
| Goose | Letta | |
|---|---|---|
| Licence | Open source | Open source |
| Pricing | open source | freemium |
| Self-hostable | Yes | Yes |
| Languages | Any language | Python, TypeScript |
| Install | brew install block-goose-cli | pip install letta |
| Keys required | None | None |
Both are open source harness options with comparable terms, so the choice comes down to which model of the problem you prefer — compare the descriptions below rather than the licence. Goose: Block's open-source on-machine agent with an extension system. Letta: Stateful agent server where memory is the primary abstraction.
Goose can run on your own infrastructure. Letta can run on your own infrastructure.
Goose is open source (open source). Letta is open source (freemium).
Every page here answers to Accept: text/markdown and returns the same content at roughly a tenth the tokens. No separate site, no toggle — same URL.
curl -s -H "Accept: text/markdown" https://newagent.build/compare/goose-vs-letta