The deciding difference is operational: DeepSeek Harness can run on infrastructure you control, OpenAI Agents SDK cannot. If that constraint is real for you, it settles the choice before anything else is considered.
Everything is a plugin — the model adapter, the tool registry, the sandbox and the agent loop itself are all swappable.
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.
Lightweight loop with handoffs, guardrails and sessions.
| DeepSeek Harness | OpenAI Agents SDK | |
|---|---|---|
| Licence | Open source | Open source |
| Pricing | open source | usage based |
| Self-hostable | Yes | No |
| Languages | TypeScript | Python, TypeScript |
| Install | npx @deepseek-ai/dsh web | pip install openai-agents |
| Keys required | None | OPENAI_API_KEY |
The deciding difference is operational: DeepSeek Harness can run on infrastructure you control, OpenAI Agents SDK cannot. If that constraint is real for you, it settles the choice before anything else is considered. DeepSeek Harness: Everything is a plugin — the model adapter, the tool registry, the sandbox and the agent loop itself are all swappable. OpenAI Agents SDK: Lightweight loop with handoffs, guardrails and sessions.
DeepSeek Harness can run on your own infrastructure. OpenAI Agents SDK is a hosted service only.
DeepSeek Harness is open source (open source). OpenAI Agents SDK is open source (usage based).
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/deepseek-harness-vs-openai-agents-sdk