Best AI coding agents

Coding agents go a step beyond autocomplete: give one a task and it reads the codebase, plans, edits across files, runs commands and tests, and reports back, sometimes opening a pull request on its own. They split by where they live: autonomous teammates (Devin), in-browser app builders (Replit Agent), and editor/terminal agents you drive yourself (Cline in VS Code, Aider in the terminal). Cline and Aider are open-source and free; you just pay for model tokens. We ranked them on autonomy, transparency, and how much supervision they still need.