# DeepSeek Harness vs Letta

Both sit in the harness layer with similar commercial terms, so the practical split is language: DeepSeek Harness targets TypeScript and Letta targets Python.

| | DeepSeek Harness | Letta |
| --- | --- | --- |
| Licence | Open source | Open source |
| Pricing | open source | freemium |
| Self-hostable | Yes | Yes |
| Languages | TypeScript | Python, TypeScript |
| Install | npx @deepseek-ai/dsh web | pip install letta |
| Keys required | None | None |

## Letta — published scores

- LoCoMo: 83.2% — self-reported, Reported in comparative write-up, 2026-08. https://mem0.ai/blog/benchmarked-openai-memory-vs-langmem-vs-memgpt-vs-mem0-for-long-term-memory-here-s-how-they-stacked-up

## Full pages

- https://newagent.build/c/deepseek-harness
- https://newagent.build/c/letta

## Machine interfaces

- `GET https://newagent.build/api/registry` — every component as JSON
- `GET https://newagent.build/api/vendors` — vendors, with the repo and releases feed to watch
- `GET https://newagent.build/api/advise?q=<plain english>` — recommended stack for a description
- `GET https://newagent.build/api/stack?<layer>=<id>&format=sh|json|md|yml|agents|env` — a stack as files
- `GET https://newagent.build/llms.txt` — the whole registry in one fetch

Any page here also returns markdown if you send `Accept: text/markdown`.