HarnessRouter

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  • HarnessRouter Community EditionOpen-source agent harness infrastructure and the Unified Harness Protocol.Product
  • Harness catalogSupported harness IDs and source-backed integration references.Harnesses
  • Care Prep BenchmarkThe same task compared across Codex, Claude Code, and Hermes configurations.Benchmarks
  • Harness rankingsPublic attributed usage across reviewed agent harnesses.Product
  • ExamplesSee how agent-backed features return finished work inside a product.Product
  • PricingPlans and usage pricing for HarnessRouter.Product
  • Hermes AgentAn open-source, persistent AI agent with memory, reusable skills, built-in tools, browser automation, scheduled tasks, and subagents.Harnesses
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The world’s first unified interface for agent harnessesPowered by UHPBacked by Y Combinator

Build agent products without handling harness engineering.

Plug Codex, Claude Code, Hermes, DeepSeek Harness, and more into your product as agent backends through one API.

Start buildingView on GitHub
01Without

Another harness means another integration.

Your product
SessionsStreamingFilesArtifactsToolsTraces
× every harness
02With HarnessRouter

One integration.
Swap with a config line.

Your product
HarnessRouter
Codex logoCodexClaude Code logoClaude CodeHermes logoHermesDeepSeek Harness logoDeepSeek Harness
HarnessRouter Community Edition - Open-source unified interface for agent harnesses | Product Hunt

Used by teams building agent-powered products

Open source at the core

Use the managed Cloud or run it yourself.

Choose the managed Cloud for the fastest path to production, or self-host the Apache 2.0 Community Edition on your infrastructure.

HarnessRouter Cloud

Start at $0, no card needed.

Explore the console and configure agents for free. Usage is drawn only while hosted tasks run; waiting is free.

Use a HarnessRouter key

Every model at its listed catalog price, no markup. Plans from $20 a month include their full price as usage.

Bring your own API keys

Your provider bills your model usage directly. You pay for Agent work only; waiting is free.

Start with HarnessRouterView Cloud pricing

Community Edition

Self-hosted

Run the same UHP interface on infrastructure you control.

  • Apache 2.0
  • Your infrastructure
  • Your keys, state, and files
View on GitHub

Benchmark · One task, same input

One task showed a ≈475× cost difference.

This is one measured workload, not a universal maximum. Harness and model both change production cost.

Observed cost spread1×

Lowest to highest configuration on this measured task.

Harness × modelRelative cost

Relative cost index from one controlled task. This is the observed spread for this workload, not a universal maximum or model ranking.

View methodology

Your first run

Build it in three steps.

Then manage your harnesses and tasks in the console.

1

Step 1 of 3

Copy and paste AGENTS.md

AGENTS.md
Copy AGENTS.md
Paste into your coding agent

Serverless agent runtime

Scale without operating the infrastructure.

Run concurrent agent workloads in isolated sandboxes. HarnessRouter provisions and operates the serverless execution infrastructure for you.

Isolated by task
Every task runs in its own sandbox with its own files and session state.
Created on demand
Sandboxes are provisioned when a task starts and scale with load; a burst queues briefly instead of failing.
Thousands of tasks at the same time
Run thousands of agent tasks in parallel. Sandboxes scale with load, and no plan puts a cap on concurrency.

Harness × model routing

Switch harnesses and models without changing your product API.

Benchmark harness × model combinations on your task, then choose the configuration you route to, all through one integration.

How HarnessRouter works

One contract between your product and a complete agent harness.

Your product

  • A web or mobile app
  • A backend service
  • A CI job
  • Another agent
HarnessRouter logo mark

HarnessRouter

UHP server
  1. 1Receives the task
  2. 2Starts the configured harness + model
  3. 3Runs it and streams progress
  4. 4Returns results and artifacts

Choose the combination

Harness × model
Harness
Model

Benchmark the pair by quality, latency, and cost.

  1. 1 Send a task
  2. 2 Run the configured harness + model
  3. 3 Progress streams back
  4. 4 Results and artifacts return
Read the Unified Harness Protocol →

Open-source starter kits

Start from a complete agent product.

Each open-source kit includes an app, a configured agent, and the skill that teaches it what to build.

View all starter kits Read the docs
Slides starter kit interface
01

Slides

Build editable presentations from a prompt.

Sheets starter kit interface
02

Sheets

Run an agent across rows and fill results live.

Dashboards starter kit interface
03

Dashboards

Turn database questions into live query-backed panels.

Videos starter kit interface
04

Videos

Plan, render, arrange, and assemble generated clips.

Customer story · Readily

“We can go from a problem and a plan to an agent in product within 24 hours.”

Co-founder and CEO, Readily (YC S23)

Readily uses HarnessRouter to bring domain expertise into production agents without rebuilding the agent runtime.

Go from plan to product

Technical Q&A

Questions engineers ask before integrating.

Direct answers about the runtime, protocol, hosting, and cost.

Product fit

What is an agent harness?

An LLM returns tokens. A harness gives it a sandbox, tools, and a loop, so it returns actual work. GPT-5.2 and Claude Opus 4.8 are models. Codex and Claude Code are harnesses.

Is HarnessRouter just another AI wrapper?

No. HarnessRouter is the execution and runtime layer between your product and supported agent harnesses. Your application sends a task and receives progress, files, artifacts, final state, and trace through one interface.

Why not integrate Codex or Claude Code directly?

You can if you only need one harness and want to own the surrounding runtime. HarnessRouter becomes useful when you need multiple harnesses, or do not want to rebuild sessions, streaming, files, resume, and traces around each integration.

What backend engineering does HarnessRouter remove?

HarnessRouter handles the agent execution lifecycle: sessions, tools, files, artifacts, streaming, cancellation, errors, resume, and traces, with hosted sandboxes on Cloud.

Interface and runtime

What is UHP?

The Unified Harness Protocol is an open standard for the interface between your product and a complete agent harness. It defines how a harness is discovered, selected, and configured, including its model, skills, tools, and MCP servers, and how tasks, sessions, streaming events, files, artifacts, cancellation, errors, and results flow between the two. Any harness that implements it is interchangeable behind your product. Read the Unified Harness Protocol

Can we switch harnesses without changing our product API?

Yes. Your product keeps the same HarnessRouter integration while selecting a supported harness by configuration. Harness-specific capabilities can differ, so you can benchmark combinations before changing production traffic.

What does HarnessRouter return to our application?

Your application can receive streamed progress and events, task status, generated files and artifacts, the final result, errors, and execution trace.

Deployment and control

What is the difference between Community Edition and HarnessRouter Cloud?

Community Edition is Apache 2.0 and runs on infrastructure you control with your own keys, state, and files. HarnessRouter Cloud runs the hosted runtime for you, with sandboxes that scale on demand.

Where do our keys, files, sessions, and state live?

With Community Edition, the runtime and application state stay in your environment. Requests to the model provider still follow the provider and credentials you choose. With Cloud, HarnessRouter operates the hosted runtime for you.

Cost and adoption

How does pricing work with our own API keys or a HarnessRouter key?

Start at $0 with no card: explore the console and configure agents. Bring your own API keys and your provider bills your model usage directly; you pay for Agent work only, and waiting is free. Use a HarnessRouter key and every model is billed at its listed catalog price with no markup; plans from $20 a month include their full price as usage. See plans and pricing

What is required to migrate an existing agent workflow?

Adopt the HarnessRouter API or UHP contract, then map your existing workflow, tools, files, and result handling to it. Community Edition and starter kits shorten the path, but your team still verifies product-specific behavior.

Put agent harnesses to work in your product.

Start with one API. Scale and optimize as your workloads grow.

Start building