A curated, verified, cross-vendor directory of AI agent harnesses — the runtime scaffolding that turns a model into an agent.
◆ 74 harnesses profiled · 9-axis capability schema · last verified 2026-07-08
The original 'AI software engineer': a cloud VM agent that plans, codes, tests and opens PRs from Slack/web/API, now spanning a whole product line (Devin cloud, Devin Desktop nee Windsurf, CLI) with ACU consumption billing ($2.00-2.25/ACU, Core $20 entry, Team $500/mo) and Cognition's own SWE-1.6 model alongside frontier models.
OpenAI's delegation-first coding agent whose cloud mode runs each task in an isolated no-internet-by-default sandbox with the repo cloned, opens PRs, does automatic PR code review on GitHub and takes tasks from ChatGPT/Slack, bundled into ChatGPT Plus/Pro/Business with rolling credit-based billing since April 2026 (the CLI companion is open source, the cloud service is not).
Google's asynchronous coding agent that clones your GitHub repo into a secure cloud VM, plans and executes tasks (bug fixes, tests) and returns PRs; free tier of 15 tasks/day with higher quotas bundled into Google AI Pro/Ultra, Gemini 3.1 Pro/3 Flash under the hood, curated MCP connections (Linear, Supabase, Neon, Context7) added Feb 2026 and an alpha REST API for Slack/Linear-driven automation.
Enterprise-focused 'Droids' platform ($1.5B valuation after April 2026 Series C): autonomous agents that execute refactors, migrations and incident investigations end-to-end across CLI, desktop, SDK and remote 'Droid Computers' cloud workloads, with both local and cloud background agents on the $20 Pro tier and adoption at Nvidia, Adobe, Morgan Stanley and MongoDB; notably model-agnostic across frontier providers.