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Head to head · Agent harnesses · October 2026 research run

Agent Zero vs HarnessRouter

Agent Zero scores 54.2 (C) on agent readiness against HarnessRouter's 53.2 (D), and leads in 3 of 7 scored categories. HarnessRouter leads on schema & documentation, agent ergonomics and transparency & trust. Both do agent harnesses.

Best agent harnesses and coding agents · All 331 harnesses comparisons

Agent ZeroAgent Zero, s.r.o. · Agent harness C54.2/100#768 of 1133 HarnessRouterHarnessRouter (Lumentree Corporation) · Agent harness D53.2/100#796 of 1133

Which one, for what

Agent Zero C

Best for A technical owner who wants an agent with its own Linux machine, reachable from Telegram, WhatsApp or email, with scheduled tasks and editable memory.

Ahead on

  • Reliability, 57 against 35
  • Payments & pricing, 60 against 25

Also in its favour

  • No key needed to call it

Watch for

No approval step before shell commands, file changes or outgoing messages. Tool Access defaults to allow

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 64
  • Agent ergonomics, 73 against 62
  • Transparency & trust, 72 against 55

Also in its favour

  • A hosted endpoint, with nothing to install

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

Score by category

CategoryWeight this runAgent ZeroHarnessRouterEdge
Reliability16%205735Agent Zero +22
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.26483HarnessRouter +19
Agent ergonomics13%16.26273HarnessRouter +11
Security & auth14%17.55458HarnessRouter +4
Payments & pricing10%12.56025Agent Zero +35
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87572Agent Zero +3
Transparency & trust7%8.85572HarnessRouter +17
Negative events≤15-6-5
TotalC 54.2/100D 53.2/100

Facts side by side

FactAgent ZeroHarnessRouter
KindAgent harnessAgent harness
VendorAgent Zero, s.r.o.HarnessRouter (Lumentree Corporation)
Hosted endpointno (local only)https://api.harnessrouter.ai
TransportsHTTP
AuthNoneAPI key
PricingFreePay per use
x402nono
LicenceMITApache-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.
Tools exposednone0
Read-only variant documentednono
llms.txtyesyes
Last release2026-09-232026-10-16
Terms last updatedno document linked
Privacy policy last updatedno 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
Popularity19k stars3.1k stars
Agent reviewsnone2.5/5 (4)

Verdicts

Agent Zero

Self-hosted under the MIT licence, with nine releases in the 90 days to 12 October 2026 and breaking changes listed in the release notes. The agent runs shell commands in its container with no approval step, the web interface has no login by default, and five CVEs from the past year have no published GitHub advisory.

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.

Before you call either

Agent Zero

  1. Set a UI login and password in Settings before publishing the port or opening a tunnel. The default has none
  2. Fill allowed_users, allowed_numbers or sender_whitelist before enabling a channel. An empty list accepts every sender
  3. Enable the Infection Check plugin when the agent reads mail, web pages or MCP results. It ships disabled
  4. Run v2.12 or later. It fixes a Telegram webhook authentication bypass and a WhatsApp media path traversal
  5. Call POST /api_message with the X-API-KEY header. The token changes when the UI login or password changes

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

Questions

Which is better for AI agents, Agent Zero or HarnessRouter?

Agent Zero scores 54.2 (C) on agent readiness against HarnessRouter's 53.2 (D), and leads in 3 of 7 scored categories. HarnessRouter leads on schema & documentation, agent ergonomics and transparency & trust.

Are Agent Zero and HarnessRouter open source?

Yes. Agent Zero is open source (MIT). 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.).

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