HarnessRouter is a unified API platform that lets developers integrate AI agent harnesses such as Codex, Claude Code, and Hermes into their products without building or maintaining the underlying infrastructure. Each agent session runs in its own isolated serverless sandbox, with HarnessRouter handling provisioning, streaming, retries, and artifact delivery. The platform includes a benchmarking and comparison tool to evaluate harness and model combinations across cost, latency, and success rate. Developers can add a single API key and ship harness-powered features in minutes rather than months.