AgentLoop vs HarnessRouter: Features, Pricing & Which Is Better (2026)
A side-by-side comparison of AgentLoop and HarnessRouter — features, pricing, and ideal use cases — to help you decide which AI tool fits your workflow.
AgentLoop
Edward Yi
AgentLoop turns a single ChatGPT plan into unattended Codex worker + independent-critic cycles that build against your local rubric until the work passes.
Key features
- Fresh Worker Per Cycle: Each build cycle spawns a clean Codex worker with fresh context so long-running loops do not accumulate stale state or memory drift.
- Independent Critic Process: A separate fresh process grades every result against your rubric so passing tests never become permission to stop looking.
- Rubric in GUIDELINES.md: Definition-of-done lives as plain Markdown in your repo and is read on every cycle, so standards persist while prompts do not.
- Evidence Carried in Files: Worker output, critic verdicts, and fixes are written to project files so the next cycle inherits the actual state of the work.
- Bounded Goal + Cycle Budget: You cap the loop with a goal.md and cycle budget so unattended runs stop at a predictable ceiling.
- MCP Status Interface: Ask ChatGPT for status through MCP so you can monitor cycles, verdicts, transcripts, and cost without opening the dashboard.
- Local-first Install: git clone the pinned v1.1.0 release and run node src/daemon.js — no npm install, no hosted workspace, MIT licensed.
Best for
- Shipping a bounded feature: Add a CSV export across UI, API, and regression suite while the critic enforces end-to-end behavior and edge cases.
- Migration work: Run an unattended migration where fresh workers apply the change and the critic verifies each step against a rubric.
- Hardening pass: Give AgentLoop a hardening goal so it iterates on defects the existing test suite misses, like malformed input handling.
- Product polish loop: Point AgentLoop at a polish goal with clear acceptance criteria and let it converge to VERDICT: PASS.
- Unattended overnight runs: Kick off a long loop, monitor cycle verdicts, and cancel from the dashboard or via MCP when the receipt looks right.
- Enforcing team standards: Codify team engineering standards in GUIDELINES.md so every worker builds against the same definition of done.
HarnessRouter
HarnessRouter
One API to run Codex, Claude Code, Hermes and other coding agents as your product backend — Y Combinator backed.
Key features
- Unified Agent API: Route to Codex, Claude Code, Hermes, Pi and other coding/autonomous agents through one endpoint
- Managed Runtime: Per-run sandbox, sessions, streaming, retries, timeouts, and permissions handled for you
- Artifact Delivery: Agents return files, code, videos, documents and other real artifacts to end users
- Execution Tracing: Step-by-step event timeline with tool calls, file changes, and agent messages for every run
- Per-Harness Settings: Configure model, tools, MCP, skills, and guardrails per harness
- Cost Controls: Budgets, alerts, and hard caps so production usage stops at your limit not your bill
- MCP Support: Bring your own MCP servers and skills into each harness
- Auto Upgrades: Platform handles upgrades, fixes, and maintenance of the agent runtimes
Best for
- Ship a website or app builder where users describe a product and get generated code/media
- Embed a digital employee that runs long-running tasks inside your SaaS
- Build model evaluation, legal, ops, or planning agents backed by frontier coding models
- Add an AI feature that produces videos, games, docs, or codebases as artifacts for end users
- Skip building sandboxing, streaming, retries, and permissions in-house
- Give internal teams a governed way to run Codex or Claude Code against production data
- Deploy an agent backend with production credits and hard cost caps