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Aider

What is Aider? An open-source terminal AI pair programming tool that edits code and commits changes in your local git repo.

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Aider — AI Glossary

Aider is an open-source AI pair programming tool that runs in your terminal and directly edits code in your local git repository. Created by Paul Gauthier, it connects to large language models — including GPT-4, Claude, and open-source models — to translate natural language instructions into working code changes, automatically creating git commits for each modification.

Why Aider Matters

Aider was one of the earliest tools to demonstrate that LLM-powered coding could go beyond autocomplete and chat — it writes, edits, and commits real code in your repo. Its open-source nature (MIT license) makes it accessible to developers who want full control over their tooling and model selection without vendor lock-in.

Because Aider supports multiple LLM backends, it serves as a practical benchmark for comparing how different models handle real-world coding tasks. The project maintains a public code editing leaderboard that tracks model performance on standardized benchmarks, making it a reference point across the agentic coding space. For a deeper look at how terminal-based AI coding tools compare, see our guide to extending AI coding workflows.

How Aider Works

Aider uses a repo map built with tree-sitter to understand your codebase structure — function signatures, class definitions, and import relationships — without stuffing entire files into the context window. When you describe a change, Aider identifies the relevant files, generates edits, applies them, and creates a git commit with a descriptive message.

Key mechanisms:

  • Multi-model support: Works with OpenAI, Anthropic, and any OpenAI-compatible API endpoint, including local models via Ollama or LiteLLM
  • Edit formats: Uses optimized diff formats (whole file, unified diff, or search/replace blocks) tuned per model for reliable code editing
  • Git integration: Every change is automatically committed, making it easy to review, revert, or build on AI-generated edits
  • Voice support: Accepts spoken instructions via built-in voice-to-text
  • Claude Code: Anthropic's terminal-based AI coding agent — similar agentic approach with deeper shell access and multi-step task execution
  • Codex CLI: OpenAI's open-source terminal coding agent — another entrant in the agentic CLI tool space
  • Agentic: The AI paradigm where tools autonomously plan and execute multi-step tasks, which Aider helped pioneer for coding workflows

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