Devin.ai (by Cognition Labs) is the pioneering 2026 autonomous AI software engineer that plans, codes, debugs, tests, and deploys full projects end-to-end in a cloud IDE. Spin up multiple parallel agents, collaborate interactively, fix CI failures automatically, handle migrations/refactors, and integrate with GitHub/Slack/Linear. With Devin 2.0+ upgrades (faster Sonnet 4.5 preview, Devin Review for smart PR analysis), it's built for real engineering velocity—great for solo devs, teams tackling complex tasks, or enterprises needing custom agents. Pay-as-you-go starts low, scales to custom.