
aider
aider is AI pair programming in your terminal
The Lens
Aider is a terminal-based AI pair programmer that edits your actual codebase. Not a chatbot that spits out snippets you copy-paste. You point it at your repo, tell it what to build or fix, and it writes the code directly into your files with proper git commits. It builds a map of your entire codebase so it understands how everything connects - even in large projects. Works with Claude, GPT-4o, DeepSeek, o3-mini, local models, basically anything. Supports 100+ languages. Has voice input, image context, linting integration, and IDE watch mode. Alternatives like Continue and Cursor offer similar AI coding but lock you into their editor. GitHub Copilot stays in VS Code's world. Aider stays in the terminal and works with whatever editor you already use. The catch: you bring your own API keys and pay for tokens directly. Heavy usage with frontier models gets expensive fast, and the terminal-first UX has a learning curve if you are not already living in the command line.
Free vs Self-Hosted vs Paid
fully freeAider is fully free and open source under the Apache 2.0 license. There is no paid tier, no cloud service, no premium features behind a paywall. The tool itself costs nothing. The real cost is the LLM API usage - you supply your own API keys from Anthropic, OpenAI, DeepSeek, OpenRouter, or any compatible provider and pay those providers directly. A typical coding session might run $0.50 to $5 in tokens depending on the model and repo size. You can use free or cheap local models via Ollama to eliminate API costs entirely, but quality drops significantly. Self-hosted option: just pip install it. No server, no docker, no infrastructure. It runs on your laptop.
Free tool, but your LLM API bill is the real price tag - budget $50-200/month for heavy use with frontier models.
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