The deciding difference is operational: Letta can run on infrastructure you control, Codex CLI cannot. If that constraint is real for you, it settles the choice before anything else is considered.
OpenAI's terminal coding agent.
Stateful agent server where memory is the primary abstraction.
| Codex CLI | Letta | |
|---|---|---|
| Licence | Open source | Open source |
| Pricing | paid | freemium |
| Self-hostable | No | Yes |
| Languages | Any language | Python, TypeScript |
| Install | npm install -g @openai/codex | pip install letta |
| Keys required | OPENAI_API_KEY | None |
The deciding difference is operational: Letta can run on infrastructure you control, Codex CLI cannot. If that constraint is real for you, it settles the choice before anything else is considered. Codex CLI: OpenAI's terminal coding agent. Letta: Stateful agent server where memory is the primary abstraction.
Codex CLI is a hosted service only. Letta can run on your own infrastructure.
Codex CLI is open source (paid). 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/codex-cli-vs-letta