# DeepSeek Harness

DeepSeek Harness is a harness option for building AI agents. Everything is a plugin — the model adapter, the tool registry, the sandbox and the agent loop itself are all swappable.

## Facts

- Layer: Harness (What thinks)
- Vendor: DeepSeek AI (github.com/deepseek-ai/deepseek-harness)
- Licence: open source
- Pricing: open source
- Self-hostable: yes
- SDKs: ts
- Install: `npx @deepseek-ai/dsh web`
- Docs: https://github.com/deepseek-ai/deepseek-harness
- Last verified: 2026-08-21

## When to reach for it

- You are choosing a harness component — what thinks.
- You need to run it on your own infrastructure, or your procurement process requires source access.
- You want to start without a commercial conversation.

## Worth knowing

Web UI first — `dsh web` serves on 127.0.0.1:3080 rather than taking over the terminal. Built on Cordis. Still a developer preview: DeepSeek warns of compatibility-breaking changes, so pin the version.

## Alternatives in the harness layer

| Option | What it does | Licence | Self-host |
| --- | --- | --- | --- |
| Claude Code | Anthropic's coding agent — terminal, IDE and SDK, with hooks, skills and MCP built in. | proprietary | no |
| Claude Agent SDK | The Claude Code loop as a library, for agents that are not about code. | proprietary | no |
| Hermes Agent | Self-improving agent from Nous Research — writes its own skills from experience and carries them forward. | open source | yes |
| OpenClaw | Self-hosted gateway putting an agent in Slack, Telegram, WhatsApp, Signal, Discord and iMessage at once. | open source | yes |
| Prime Agent | Prime Intellect's recursive-language-model harness — a persistent IPython kernel is the only tool, sub-agents are function calls. | open source | yes |
| OpenAI Agents SDK | Lightweight loop with handoffs, guardrails and sessions. | open source | no |
| Codex CLI | OpenAI's terminal coding agent. | open source | no |
| OpenCode | Open-source terminal coding agent, provider-agnostic. | open source | yes |
| Goose | Block's open-source on-machine agent with an extension system. | open source | yes |
| Letta | Stateful agent server where memory is the primary abstraction. | open source | yes |
| Roll your own loop | No harness. A while-loop, a model call and your own tool dispatch. | open source | yes |

Head to head:

- https://newagent.build/compare/deepseek-harness-vs-claude-code
- https://newagent.build/compare/deepseek-harness-vs-claude-agent-sdk
- https://newagent.build/compare/deepseek-harness-vs-hermes-agent
- https://newagent.build/compare/deepseek-harness-vs-openclaw
- https://newagent.build/compare/deepseek-harness-vs-prime-agent
- https://newagent.build/compare/deepseek-harness-vs-openai-agents-sdk
- https://newagent.build/compare/deepseek-harness-vs-codex-cli
- https://newagent.build/compare/deepseek-harness-vs-opencode

## Add it to a stack

```bash
curl -fsSL "https://newagent.build/api/stack?harness=deepseek-harness&format=sh" | sh
```

## 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

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