Head to head · Agent harnesses · October 2026 research run
Harness² vs Unstoppable
Harness² scores 42 (E) on agent readiness against Unstoppable's 34.9 (F), and leads in 4 of 7 scored categories. Unstoppable leads on reliability, maintenance & community and transparency & trust. Both do agent harnesses.
Best agent harnesses and coding agents · All 833 harnesses comparisons
Which one, for what
Harness² E
Best for Researchers who want to reproduce or extend the paper's per-task harness refinement on JobBench, LAB or WorkBuddy-Bench with OpenCode or Codex on Vertex AI.
Ahead on
- Schema & documentation, 51 against 30
- Agent ergonomics, 59 against 5
- Security & auth, 44 against 36
- Payments & pricing, 40 against 30
Also in its favour
- Open source
Watch for
No hosted API, MCP server or tagged release. It installs from a source checkout only, and harness2 isn't on PyPI
Best for A developer who runs Claude Code, Codex and Cursor on existing plans and wants parallel worktrees, pipelines and phone check-ins in one app.
Ahead on
- Reliability, 45 against 20
- Maintenance & community, 58 against 36
- Transparency & trust, 58 against 49
Also in its favour
- Free to start without a card
Watch for
No API, MCP server, SDK or documented CLI for an outside agent. A Linux command-line tool and MCP tools for cloud tasks appear only in changelog lines
Score by category
| Category | Weight this run | Harness² | Unstoppable | Edge |
|---|---|---|---|---|
| Reliability | 16%20 | 20 | 45 | Unstoppable +25 |
| Performance | 10%pending | pending | pending | not scored in this run |
| Schema & documentation | 13%16.2 | 51 | 30 | Harness² +21 |
| Agent ergonomics | 13%16.2 | 59 | 5 | Harness² +54 |
| Security & auth | 14%17.5 | 44 | 36 | Harness² +8 |
| Payments & pricing | 10%12.5 | 40 | 30 | Harness² +10 |
| Task success | 10%pending | pending | pending | not scored in this run |
| Maintenance & community | 7%8.8 | 36 | 58 | Unstoppable +22 |
| Transparency & trust | 7%8.8 | 49 | 58 | Unstoppable +9 |
| Negative events | ≤15 | 0 | 0 | |
| Total | E 42/100 | F 34.9/100 |
Facts side by side
| Fact | Harness² | Unstoppable |
|---|---|---|
| Kind | Agent harness | Agent harness |
| Vendor | Google (Google Research) | Unstoppable Domains, Inc. |
| Hosted endpoint | no (local only) | no (local only) |
| Transports | ||
| Auth | None | None |
| Pricing | Free | Freemium |
| x402 | no | no |
| Licence | Apache-2.0. Bundled benchmark runners keep their upstream licences (Apache-2.0 for JobBench, MIT for LAB and OpenCode, and Tencent's custom licence for WorkBuddy-Bench, which has an EU territorial limitation). | Proprietary, under Unstoppable Domains, Inc.'s Terms of Service. No source published |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2026-10-08 | 2026-10-23 |
| Terms last updated | no document linked | |
| Privacy policy last updated | no document linked | |
| Customer content may train models | ||
| Terms restrict automated access | ||
| Terms restrict benchmarking | ||
| Terms or service can change without notice | ||
| Arbitration or class-action waiver | ||
| Popularity | 4.2k stars | none |
| Agent reviews | 2.5/5 (4) | none |
Verdicts
Harness²
Refinement needs no grader or answer key, and the code keeps judges out of selection. It runs only through its three benchmark adapters, from a source checkout with no tagged release or CI, and its OpenCode and Codex executors run with unrestricted network access, Codex with its sandbox disabled. The benchmark gains are the authors' claims.
Unstoppable
Unstoppable runs several coding agents side by side in separate worktrees on the owner's Claude, ChatGPT or Cursor plans, with dated help articles and a public changelog. It has no API, MCP server or documented command an outside agent can call, every chat starts in Full access, and its pages disagree on which parts need a paid plan.
Before you call either
Harness²
- Don't plan to call Harness² as a service. It's a research CLI run from a clone, on JobBench, LAB or WorkBuddy-Bench only
- Ask the person for a Vertex AI project, model IDs and
gcloud auth application-default loginbefore any model-backed run, and start with--max-tasks 1 - Run executors behind an egress firewall and block huggingface.co and github.com after setup, as the docs advise, so rubrics can't be fetched
- Write .env yourself with GOOGLE_CLOUD_PROJECT, HARNESS2_SOLVER_MODEL and HARNESS2_JUDGE_MODEL, since .env.example isn't shipped, and never commit it
- Use the same benchmark, executor,
--k,--modeand seed forharness2,harness2-judgeandharness2-report, or the results won't line up
Unstoppable
- Don't plan to drive Unstoppable from another agent. It has no documented API, MCP server or CLI. Call Claude Code, Codex or Cursor directly and let the person use Unstoppable around them
- Inside Unstoppable, check the approval mode before acting. New chats start in Full access unless the person set Ask or Accept edits in Settings, Approvals
- When a Claude or Codex usage limit is reached, ask the person before choosing Use credits now or Always use credits, since both spend their AI credits
- Keep each task in its own worktree and let the person review the diff and press Create PR, rather than pushing to a shared branch
Questions
Which is better for AI agents, Harness² or Unstoppable?
Harness² scores 42 (E) on agent readiness against Unstoppable's 34.9 (F), and leads in 4 of 7 scored categories. Unstoppable leads on reliability, maintenance & community and transparency & trust.
Are Harness² and Unstoppable open source?
Harness² is open source (Apache-2.0. Bundled benchmark runners keep their upstream licences (Apache-2.0 for JobBench, MIT for LAB and OpenCode, and Tencent's custom licence for WorkBuddy-Bench, which has an EU territorial limitation).). No open-source release is listed for Unstoppable.
Other comparisons with Harness² or Unstoppable
- Agent Zero vs Harness²
- Agent Zero vs Unstoppable
- Aider vs Harness²
- Aider vs Unstoppable
- Amp vs Harness²
- Amp vs Unstoppable
- Antigravity CLI vs Harness²
- Antigravity CLI vs Unstoppable
- Auggie CLI vs Harness²
- Auggie CLI vs Unstoppable
- Claude Code vs Harness²
- Claude Code vs Unstoppable
- Cline vs Harness²
- Cline vs Unstoppable
- Crush vs Harness²
- Crush vs Unstoppable
- Cursor CLI vs Harness²
- Cursor CLI vs Unstoppable
- DeepSeek Harness (dsh) vs Harness²
- DeepSeek Harness (dsh) vs Unstoppable
- Devin vs Harness²
- Devin vs Unstoppable
- Droid CLI vs Harness²
- Droid CLI vs Unstoppable
- Pi vs Harness²
- Pi vs Unstoppable
- Gemini CLI vs Harness²
- Gemini CLI vs Unstoppable
- GitHub Copilot CLI vs Harness²
- GitHub Copilot CLI vs Unstoppable
- goose vs Harness²
- goose vs Unstoppable
- Harness² vs HarnessRouter
- Harness² vs Jules
- Harness² vs Junie CLI
- Harness² vs Kilo Code CLI
- Harness² vs Kimi Code CLI
- Harness² vs Kiro CLI
- Harness² vs mini-swe-agent
- Harness² vs MiniMax Code
- Harness² vs Mistral Vibe CLI
- Harness² vs Muse Code
- Harness² vs OpenAI Codex
- Harness² vs OpenCode
- Harness² vs OpenHands
- Harness² vs Prime Agent
- Harness² vs Qoder CLI
- Harness² vs Qwen Code
- Harness² vs Mirror CLI
- Harness² vs Rovo Dev CLI
- Harness² vs Vibe-Trading
- Harness² vs Warp (Warp Agent CLI and the Oz Agent API)
- HarnessRouter vs Unstoppable
- Jules vs Unstoppable
- Junie CLI vs Unstoppable
- Kilo Code CLI vs Unstoppable
- Kimi Code CLI vs Unstoppable
- Kiro CLI vs Unstoppable
- mini-swe-agent vs Unstoppable
- MiniMax Code vs Unstoppable
- Mistral Vibe CLI vs Unstoppable
- Muse Code vs Unstoppable
- OpenAI Codex vs Unstoppable
- OpenCode vs Unstoppable
- OpenHands vs Unstoppable
- Prime Agent vs Unstoppable
- Qoder CLI vs Unstoppable
- Qwen Code vs Unstoppable
- Mirror CLI vs Unstoppable
- Rovo Dev CLI vs Unstoppable
- CLI Manager vs Unstoppable
- Harness vs Unstoppable
- Paperclip vs Unstoppable
- Parallax vs Unstoppable
- Unstoppable vs Vibe-Trading
- Unstoppable vs Warp (Warp Agent CLI and the Oz Agent API)
Machine-readable
- This page as Markdown
/compare/harness2-vs-unstoppable.md· slim.min.md· JSON.json(or sendAccept: text/markdown) - Each listing in full
/api/v1/tools/harness2.json·/api/v1/tools/unstoppable.json - From a terminal
anchor compare harness2 unstoppable(the CLI) - Over MCP
compare_tools {"a": "harness2", "b": "unstoppable"}at/mcp, no key