Aider

What it is

Aider presents itself as AI pair programming in the terminal. It is built for two kinds of work: starting a new project, and building on an existing codebase^[1]. Its public repository, Aider-AI/aider, was created on 9 May 2023 and has since passed 50,000 stars; the project describes itself there as "AI pair programming in your terminal"^[2].

How it works

The tool's central claim is that it looks at the whole repository rather than a single file. Aider builds a map of the entire codebase, which the project says is what lets it work well in larger projects^[1]. It supports more than 100 code languages, among them Python, JavaScript, Rust, Ruby, Go, C++, PHP, HTML and CSS^[1]. The editing itself is done by a language model, either a cloud service or a local one^[1].

Changes are not left loose in the working directory. Aider integrates with git and commits changes automatically with what the project calls sensible commit messages, so familiar git tools can be used to diff, manage and undo the AI's edits^[1]. Version history therefore stays both the record of what the assistant did and the way to roll it back.

Working with it

Aider runs as a chat in a terminal, but it accepts more than typed text. It can be used from inside an IDE or editor by adding comments to the code to request changes^[1]. Images and web pages can be added to the chat to supply visual context such as screenshots or reference documents^[1]. It also supports voice-to-code, so features, test cases or bug fixes can be requested by speaking^[1].

The tool checks its own work: it lints and tests the code every time it makes changes, and can fix problems found by linters and test suites^[1]. It can also drive a language model through its web chat interface, which streamlines copying and pasting between the terminal and a browser^[1].

Models and installation

Aider connects to cloud and local LLMs. The project's site says it works best with Claude 3.7 Sonnet, DeepSeek R1 and Chat V3, and OpenAI's o1, o3-mini and GPT-4o^[1]. Its home page reports 6.8 million installs and 15 billion tokens processed per week^[1].

Installation runs through the aider-install package; after that the tool is launched from inside the project directory with a model and an API key^[1].

Where it sits

Two design decisions shape Aider's place among coding assistants: it lives in the terminal, and it treats git as the boundary of its work. Because its commits are ordinary commits, a developer can review, revert or branch them with the same tools used for human-written code^[1]. Because the codebase map is built for the whole repository rather than one file, the tool is aimed at projects that are already substantial rather than single scripts^[1]. And because it can talk to local models as well as cloud ones, one interface covers both settings^[1]. The combination keeps the assistant close to the workflow many developers already have — a shell, a repository and its history — instead of asking them to move into a separate application.