DeepSeek Harness
Open-source agent runtime from DeepSeek. Every piece — models, tools, sandboxes, UI — is a plugin. MIT-licensed developer preview launched August 13, 2026.
Updated 2026-08-17
Yes. DeepSeek Harness is free to use.
Listed pricing: Free (MIT). Inference is whatever model you plug in — DeepSeek V4-Flash and V4-Pro are the vendor pairing.
Overview
DeepSeek Harness is a developer-preview agent runtime, announced August 13, 2026 alongside DeepSeek-V4-Pro. The official page and the GitHub repo use the same slogan: "Everything is a plugin." Models, tools, skills, sessions, sandboxes, filesystems, loops, orchestration, and UI are described as swappable pieces on a Cordis kernel. License is MIT. The public repo is github.com/deepseek-ai/deepseek-harness.
Quick start from the vendor: npx @deepseek-ai/dsh web for a local UI, or clone and use pnpm. Modes listed in the preview include Standard, Code, Minimal, and Creator. Every run is supposed to leave an append-only event stream; Trajectory view is the replay and fork surface. V4-Pro launch coverage notes that some of the published Pro agent scores were run in Minimal mode — that is a vendor/press claim, not an independent bake-off.
This is infrastructure, not a hosted assistant. You still pay for whatever model you point it at. DeepSeek's own pairing is V4-Flash (high concurrency, lower price) and V4-Pro (harder agent tasks). It is the open-runtime counterpart to Claude Code or Codex, not a replacement for the DeepSeek API.
Keep the repo and deepseek.com/harness as the live pages. Star counts move daily; do not treat a screenshot of GitHub as a durable fact. Confirm the latest tag and the npx package name on the README before you paste a command into a tutorial.
Is DeepSeek Harness free?
Yes. DeepSeek Harness is free to use.
What the free tier covers: The runtime is free. Model tokens are billed by whichever API you configure.
Listed pricing: Free (MIT). Inference is whatever model you plug in — DeepSeek V4-Flash and V4-Pro are the vendor pairing.
Pricing verified . That is the date the plans were last re-checked against the vendor's own pages, not today's date. Confirm on the official site before you pay.
DeepSeek Harness pricing
| Plan | Price | What's included |
|---|---|---|
| Open source | $0 | MIT license, source on GitHub. You bring model keys. Developer preview (v0.1) as of August 13, 2026. |
MIT license, source on GitHub. You bring model keys. Developer preview (v0.1) as of August 13, 2026.
Pricing verified . That is the date the plans were last re-checked against the vendor's own pages, not today's date. Confirm on the official site before you pay.
Is DeepSeek Harness worth it?
Worth it for Developers who want an MIT-licensed agent runtime they can recompose, and who will bring their own model keys.
You can test that on the free tier before paying anything. The recorded trade-offs are listed below, and any one of them can settle the question on its own.
The 8.4/10 AI Score is an editorial read of published capability, price and shipping pace. Nobody here has hands-on hours with DeepSeek Harness. How we verify.
Worth it if
The strengths recorded against this entry.
- MIT-licensed; you can read and fork the loop
- Plugin model means you are not stuck on DeepSeek weights
- Launched next to V4-Pro, so the vendor's own agent scores have a named runtime
- Local npx path, no hosted lock-in for the runtime itself
Not worth it if
Any one of these blocks your use case.
- Developer preview v0.1 as of August 13, 2026 — expect breakage
- You still pay for inference, and you assemble the stack
- Not a product with an SLA or a consumer UI beyond the local web mode
- "Rival to Claude Code" is press framing, not a documented feature-parity claim
What sets DeepSeek Harness apart
- Every capability is a plugin on the Cordis kernel
- Append-only session logs with a Trajectory view for replay and fork
- Standard, Code, Minimal, and Creator modes in the preview
- Local npx start; no hosted lock-in for the runtime itself
Key features
Plugin architecture
Vendor description: every component (models, tools, skills, sessions, sandboxes, filesystems, loops, orchestration, UI) is a plugin on the Cordis meta-framework.
Traceable sessions
Append-only session logs. Trajectory view is documented for replay and fork.
Modes
Preview lists Standard, Code, Minimal, and Creator. Press notes that some V4-Pro agent benchmarks used Minimal mode.
Local quick start
npx @deepseek-ai/dsh web, or git clone plus pnpm, per the Aug 13 preview page.
How it compares
| Tool | Best for | Pricing | Score |
|---|---|---|---|
| DeepSeek Harness | Developers who want an MIT-licensed agent runtime they can recompose, and who will bring their own model keys. | Free (MIT). Inference is whatever model you plug in — DeepSeek V4-Flash and V4-Pro are the vendor pairing. | 8.4/10 |
| DeepSeek | Developers and teams running heavy coding or reasoning workloads who want frontier-level model performance without frontier-level API bills. | Free chat + API from $0.27/M input tokens | 8.9/10 |
| Claude Code vs Claude Code → | Developers who want an agent that works inside an existing repo and toolchain rather than in a hosted editor, and who already pay for a Claude plan. | Included with Claude Free, Pro, Max, Team and Enterprise plans | 9.3/10 |
| OpenAI Codex | Teams already standardised on ChatGPT who want the coding agent bundled with the seats they pay for, and who want the same agent in a terminal, an editor and a pull request. | Included with ChatGPT Free, Go, Plus, Pro, Business, Edu and Enterprise plans | 8.8/10 |
| Grok Build | Developers who want a terminal agent on Grok 4.6 with a plan you approve before edits. | Product page says you can try it free; SuperGrok and X Premium+ still listed as paid paths | 8.2/10 |
Compare head-to-head
Related reading
DeepSeek Harness: Open Agent Runtime, How to Run It
DeepSeek open-sourced an MIT-licensed agent runtime on August 13. Plugin architecture, Trajectory replay, and the npx command to run it locally.
Gemini 3.7 Flash: What Shipped and What It Costs
Google launched Gemini 3.7 Flash on August 13. Intro API price is $0.75/$3.75 per 1M tokens through December 31, 2026, then $1.50/$7.50.
Grok 4.6 vs 4.5: Pricing, Evals, Where It Ships
xAI shipped Grok 4.6 on August 12. Official $2/$6 API price, vendor evals vs 4.5, and same-week placement in Build, Cursor, and Copilot.
Ready to try DeepSeek Harness?
Head to the official site to start with DeepSeek Harness — pricing and plans are listed above.
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