Aider is “AI pair programming in your terminal”: an open-source community project that edits code in your local git repository in collaboration with an LLM. Its repository has around 44,000 GitHub stars, making it one of the most-starred tools in the category.
models and pricing
Aider is free; you pay only your own LLM API costs. It connects to almost any model through provider-prefixed ids, hosted or local, so an Ollama model on your own hardware works the same way a frontier API does.
what it’s good at
Aider commits automatically with sensible messages as it works, so every change lands in git history. A repository map helps it navigate large codebases, it supports over 100 languages, and it can take voice, images, and web pages as context. After editing it can lint and test the result automatically.
Aider in crystl
Aider runs in a crystl shard with its own model selection and activity visibility, and a prompt can be handed to it at launch for one-shot worker runs.
Crystl treats its compatibility as partial because aider exposes no hooks: no approval cards, no readable transcript, and no resume by session id. A worker reports done when its process exits.
The profile describes what crystl has tested; it never supplies a command, hook script, or launch setting. Those remain local to the Crystl installation.