Aider: Terminal AI Pair Programming and Quickstart Guide

What it is

Aider is an open-source command-line tool designed to bring artificial intelligence directly into a developer’s terminal for pair programming. In traditional software development, pair programming is a collaborative technique where two engineers work together at a single keyboard to write, review, and refine code in tandem. Aider recreates this workflow by allowing a developer to collaborate directly with a large language model (LLM) inside their shell.

The utility is built to assist programmers whether they are starting a fresh project from scratch or maintaining and building upon an established codebase. Instead of requiring a standalone graphical editor or separate web window, Aider operates directly within the command line, enabling developers to prompt AI models, apply edits, and manage changes without abandoning their terminal environment.

Distributed under the open-source Apache-2.0 license, Aider has seen significant adoption across the developer ecosystem. According to the project README and official website, Aider has accumulated 44,000 GitHub stars and logged more than 6.8 million installations via pip from the Python Package Index (PyPI). Furthermore, project documentation notes that Aider users process approximately 15 billion tokens on a weekly basis, that the application ranks among the top 20 applications on the OpenRouter platform, and that 88% of the new code in its last release was written by Aider itself.

What it can do

Aider incorporates a variety of features aimed at making AI-assisted software engineering reliable, modular, and easy to inspect:

• Repository Mapping: Working in substantial codebases can be difficult for language models because critical definitions and logic are often scattered across hundreds of files. Aider addresses this by building an architectural map of the entire codebase. This repository map helps the AI understand the broader project structure and dependencies, enabling it to navigate and edit larger projects more effectively.
• Broad Programming Language Support: The tool is versatile and supports more than 100 programming languages. Supported languages include Python, JavaScript, Rust, Ruby, Go, C++, PHP, HTML, CSS, and dozens more.
• Automated Git Integration: Aider integrates directly with Git version control. Every time the model makes changes to project files, Aider automatically commits the updates with sensible commit messages. This allows developers to use familiar Git commands to view diffs (line-by-line differences), monitor changes, manage commit histories, and easily undo any alterations they do not want to keep.
• Model Flexibility: Aider connects to a wide variety of large language models, including both commercial cloud-based APIs and locally hosted LLMs. According to the project documentation, it works best with models such as Claude 3.7 Sonnet, DeepSeek R1 and Chat V3, and OpenAI o1, o3-mini, and GPT-4o, but it can interface with almost any model.
• Web Chat and Browser Integration: While Aider is optimized to work directly with model APIs, it also accommodates developers who prefer using web-based chat interfaces. The tool streamlines the process of copying and pasting code context and edits back and forth between the terminal and a browser window.
• In-Editor Collaboration: Developers are not forced to abandon their preferred integrated development environment (IDE) or text editor. Aider can watch local files, allowing programmers to add instructions as comments directly in their code for Aider to detect and execute.
• Multimodal and Web Context: Users can provide additional visual and technical references to the model by attaching images, screenshots, or web page URLs directly into the chat session.
• Voice-to-Code Functionality: Rather than typing out every prompt, users can speak directly to Aider using their microphone. The tool accepts voice input to request new features, discuss test cases, or describe bug fixes.
• Automated Linting and Test Fixing: Aider automatically runs linters (tools that check code for syntax and style issues) and test suites whenever it makes code updates. If any errors or broken tests are detected, Aider reads the error messages and works to fix the problems autonomously.

How to get started

Getting started with Aider requires a working Python installation and access to a terminal. The setup process uses Python’s package manager to install the installer tool, which then configures the environment. Once installed, users navigate into their code directory and launch the application alongside the model flags and API keys of their choice.

The project README outlines the following installation and execution commands:

python -m pip install aider-install
aider-install

# Change directory into your codebase
cd /to/your/project

# DeepSeek
aider --model deepseek --api-key deepseek=<key>

# Claude 3.7 Sonnet
aider --model sonnet --api-key anthropic=<key>

# o3-mini
aider --model o3-mini --api-key openai=<key>

In this sequence, python -m pip install aider-install installs the package installer, and aider-install completes the necessary setup. Switching into the target repository using cd /to/your/project ensures that Aider has access to local files and Git version history. From there, developers run aider with the model name flag (such as --model deepseek, --model sonnet, or --model o3-mini) and supply the corresponding API key.

The project website hosts extensive documentation for further configuration, including an Installation Guide, a Usage Guide, tutorial videos, configuration options, guidance on connecting various LLMs, troubleshooting resources, and an FAQ.

Pricing and requirements

Aider is released as open-source software under the Apache-2.0 license. Regarding costs and plans, pricing and plans are subject to the official page at the official Aider website.

To run Aider, developers must meet several standard technical requirements outlined in the project documentation:

• Operating Environment: A command-line terminal environment with Python and the pip package manager installed.
• Version Control: A local project directory, ideally initialized as a Git repository so that Aider can perform automatic commits, track diffs, and enable change rollbacks.
• Model Credentials: Valid API keys for the chosen model providers (such as Anthropic, OpenAI, or DeepSeek) or an operational local LLM setup.
• Development Tooling: Any testing frameworks or linters that developers wish to run should be configured within the project so Aider can detect issues and attempt automated fixes.

Who it is for

Aider is designed for software engineers, hobbyist coders, and technical teams looking for a terminal-centered AI programming tool. It is particularly suited for:

• Command-Line Developers: Engineers who spend the majority of their time in terminal windows and prefer interacting with AI without navigating heavyweight standalone GUI apps.
• Developers with Existing Repositories: Programmers working on mature or large-scale projects who benefit from codebase mapping to keep AI edits aware of file relationships across the codebase.
• Git-Centric Programmers: Developers who prioritize disciplined change tracking, clear commit histories, and the ability to easily revert experimental AI code.
• Polyglot Engineers: Programmers working across multiple programming languages—such as Python, Rust, Go, JavaScript, C++, or PHP—who want a unified coding assistant.
• Model-Flexible Users: Developers who prefer choosing between multiple commercial API providers and locally run language models rather than being locked into a single provider.
• Workflow Automators: Users who value automated feedback loops that run linters and test suites to catch and fix bugs immediately after edits are made.

Alternatives

Cline is an open-source AI coding assistant designed to assist developers with programming tasks.

Continue is an open-source coding tool that provides AI support for software development workflows.

Sources

• https://github.com/Aider-AI/aider
• https://aider.chat/
• https://github.com/cline/cline
• https://github.com/continuedev/continue