Devin
Cognition's autonomous AI engineer that plans, codes, tests, debugs, and opens PRs unattended. Now shipped alongside Windsurf (acquired July 2025) as the async half of Cognition's stack — Devin runs async tasks, Windsurf is the in-editor surface.
Cursor
VS Code fork with deep AI editing, multi-file context, and a powerful agent mode. The most popular AI editor by mindshare.