agent-harness vs harnessrouter
Agent harness integrations compared
agent-harness is a Rust library for running coding agents through a shared interface and typed event stream. harnessrouter is a self-hosted Python service that exposes multiple agent harnesses through a unified API; the main difference is library-level integration versus a deployed backend service.
agent-harness: Run Claude Code and Other Agents from Rust
agent-harness is a Rust framework for calling Claude Code, OpenAI Codex, OpenCode, and compatible agents from code. It normalizes their output into one typed event stream so applications can switch agents without changing their event-handling loop.
harnessrouter: Unify Agent Harnesses Behind One API
HarnessRouter is a self-hosted Python service built around the Unified Harness Protocol (UHP), with an OpenAI Responses-compatible API for agent harnesses such as Codex and Claude Code. It gives product teams one interface for sessions, streaming, files, cancellation, and failures.
| agent-harness | harnessrouter | |
|---|---|---|
| Language | Rust | Python |
| License | Apache-2.0 | Apache-2.0 |
| Stars | 2 | 3.1k |
| Forks | 0 | 345 |
| Last analyzed | Nov 9, 2026 | Oct 20, 2026 |
Key differences
- agent-harness provides a Rust interface for embedding agent runs in applications, while harnessrouter provides a Python service for clients to call over an API.
- agent-harness normalizes output into events and includes a tool loop for OpenAI-compatible models; harnessrouter focuses on shared sessions, streaming, files, cancellation, and protocol conformance.
- agent-harness supports existing agent CLIs, ACP agents, and OpenAI-compatible chat APIs; harnessrouter lists harnesses such as Codex, Claude Code, Hermes, and PI.
- agent-harness reports readiness but does not install agent software; harnessrouter installs harness CLIs at first launch and offers Docker deployment with persistent storage.
- Both projects use the Apache-2.0 license, but agent-harness is described as being in active development with an API that may change.
- agent-harness is aimed at Rust application developers; harnessrouter is aimed at product and infrastructure teams running agent tasks on their own systems.
Choose agent-harness if you…
- need a Rust library to embed agent runs in an application.
- want a shared event-processing loop across supported agent backends.
- want to expose in-process functions to agents through Rust tool integrations.
Choose harnessrouter if you…
- need a self-hosted API for integrating multiple agent harnesses.
- want persistent sessions, file handling, streaming, and cancellation through a shared service.
- want to work with the Unified Harness Protocol implementation or its conformance suite.
Compare the numbers side by side, or add more projects
This comparison is generated with AI from the OSRepos analyses of both projects. Always check each project's repository and documentation before choosing.