Aider predates most of the agentic coding tools that get hype now, and it earned its place by being unapologetically opinionated about how a coding agent should behave. Every change becomes a commit; every commit has a message the agent generated; every session ends with a clean git history that doubles as an audit log. It is the tool that taught a generation of CLI users how to work with AI agents responsibly.
If Claude Code is the polished default and Cursor is the editor-native option, Aider is the open-source minimalist that shipped first and refuses to add features that do not earn their keep. The whole tool fits in a small mental model, and the small mental model is the point.
§01Why it still matters
The thing Aider got right before anyone else did was treating git as the memory system. Every change becomes a commit. Every commit has a generated message. The session ends and the audit log is already written, in the same place you would normally look for one, and the rollback path for a wrong move is the same git reset command you already know.
The other choice that has aged well is being model-agnostic. Aider talks to Claude, GPT, and local models through Ollama, which is useful both when you are offline and when you want to compare models on the same task without rewriting your prompt. The scope of the tool stays deliberately tight: no skills, no hooks, no MCP, just an agent that edits files and commits. The minimalism is what makes the codebase readable; you can hold the whole loop in your head.
§02When to reach for it
Aider shines for surgical changes where you want every step to land in git history with a sensible message. Bug fixes, small refactors, the kind of work you might want to bisect later. It is also the right tool when you are working with local models, or in environments where Claude Code's cloud connection is awkward.
§03Setup
pip install aider-chat
# point at a model
export ANTHROPIC_API_KEY=...
# in your repo
aider # interactive
aider --message "fix the bug" # one-shot
§04Caveats
The minimalism that makes Aider readable is also the ceiling on what it does well. For big multi-file work, Claude Code or Cursor is more ergonomic. Aider expects you to add files to the chat manually with /add rather than auto-discovering them, which is deliberate and sometimes tedious. And the auto-commit-per-change behavior is great until you want to squash a session into a single commit, at which point git rebase -i is your friend.