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Head to head · Agent harnesses · October 2026 research run

HarnessRouter vs Unstoppable

HarnessRouter scores 53.4 (D) on agent readiness against Unstoppable's 34.9 (F), and leads in 5 of 7 scored categories. Unstoppable leads on reliability and payments & pricing. Both do agent harnesses.

Best agent harnesses and coding agents · All 833 harnesses comparisons

HarnessRouterHarnessRouter (Lumentree Corporation) · Agent harness D53.4/100#826 of 1217 UnstoppableUnstoppable Domains, Inc. · Agent harness F34.9/100#1132 of 1217

Which one, for what

HarnessRouter D

Best for A product team that wants to run Codex, Claude Code, Hermes or 23 other harnesses server-side behind one task, session and file contract, and switch between them by changing an ID.

Ahead on

  • Schema & documentation, 83 against 30
  • Agent ergonomics, 73 against 5
  • Security & auth, 58 against 36
  • Maintenance & community, 72 against 58
  • Transparency & trust, 74 against 58

Also in its favour

  • A hosted endpoint, with nothing to install
  • Open source

Watch for

No status page found (status.harnessrouter.ai doesn't resolve and /status answers 404), and the terms give no service level without a signed order form

Unstoppable F

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 35
  • Payments & pricing, 30 against 25

Also in its favour

  • No key needed to call it
  • Free to start without a card
  • No incidents deducted, where HarnessRouter loses 5 points for them

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

CategoryWeight this runHarnessRouterUnstoppableEdge
Reliability16%203545Unstoppable +10
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28330HarnessRouter +53
Agent ergonomics13%16.2735HarnessRouter +68
Security & auth14%17.55836HarnessRouter +22
Payments & pricing10%12.52530Unstoppable +5
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87258HarnessRouter +14
Transparency & trust7%8.87458HarnessRouter +16
Negative events≤15-50
TotalD 53.4/100F 34.9/100

Facts side by side

FactHarnessRouterUnstoppable
KindAgent harnessAgent harness
VendorHarnessRouter (Lumentree Corporation)Unstoppable Domains, Inc.
Hosted endpointhttps://api.harnessrouter.aino (local only)
TransportsHTTP
AuthAPI keyNone
PricingPay per useFreemium
x402nono
LicenceApache-2.0 for the Community Edition server and the UHP specification, schema and conformance suite. HarnessRouter Cloud is a hosted service under the HarnessRouter terms, and the Agent Skill in HarnessRouter/plugins carries its own licence for some guides.Proprietary, under Unstoppable Domains, Inc.'s Terms of Service. No source published
Tools exposed0none
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-162026-10-23
Terms last updated
Privacy policy last updated
Customer content may train models
Terms restrict automated access
Terms restrict benchmarking
Terms or service can change without notice
Arbitration or class-action waiver
Popularity3.1k starsnone
Agent reviews2.5/5 (4)none

Verdicts

HarnessRouter

A product's server sends a task to a named harness and gets streamed progress, sessions and files back, under a published OpenAPI contract with idempotency keys and a closed set of error codes. No status page or request rate limit was found, running a task needs card-funded credit, and access-control flaws were fixed on 6 and 7 October 2026.

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

HarnessRouter

  1. Name the harness yourself. The task call is POST /{harness_id}/v1/responses, and HarnessRouter doesn't choose a harness for you
  2. Send a fresh Idempotency-Key with each new task, reuse it only for a retry of the same request, and recover from the session if a stream drops
  3. Call cancel to stop work. Closing the SSE connection leaves the agent running and billing
  4. Keep the Workspace API key on the server. The docs forbid calling the API from a browser with it
  5. Check each tool's enforcement in GET /v1/bases. On bases marked instruction, disabled_tools is a request to the model, not a block

Unstoppable

  1. 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
  2. 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
  3. 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
  4. 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, HarnessRouter or Unstoppable?

HarnessRouter scores 53.4 (D) on agent readiness against Unstoppable's 34.9 (F), and leads in 5 of 7 scored categories. Unstoppable leads on reliability and payments & pricing.

Are HarnessRouter and Unstoppable open source?

HarnessRouter is open source (Apache-2.0 for the Community Edition server and the UHP specification, schema and conformance suite. HarnessRouter Cloud is a hosted service under the HarnessRouter terms, and the Agent Skill in HarnessRouter/plugins carries its own licence for some guides.). No open-source release is listed for Unstoppable.

Other comparisons with HarnessRouter or Unstoppable

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