Aider is the most popular open-source AI coding agent with 42K+ GitHub stars. Its architecture score of 61/100 places it among the top open-source agents, and its git-native workflow is unique.
Git-Native: Aider auto-commits changes, making every modification reversible. This git-first approach means you can experiment freely — roll back any change with a single command.
Architect Mode: Aider's two-model pipeline uses a strong model for planning and a weaker model for implementation, optimizing cost without sacrificing quality.
Repo Map: Aider builds a map of your codebase so it understands file relationships — essential for multi-file changes.
Aider works best with open-source models like DeepSeek V4 (72 SWE-bench) or Qwen 3.6. Total cost: $0 (agent) + LLM API costs (~$0.3-0.5/M tokens).