Plandex

Plandex is an open-source, terminal-based AI coding engine built in Go, designed for large coding tasks that span dozens of files and many steps. It plans changes before implementing them, keeps AI-generated edits in a cumulative diff sandbox so you can review and selectively apply them, and builds fast tree-sitter project maps across 30+ languages so it stays reliable in big codebases. Model packs let you mix and match providers — Anthropic, OpenAI, Google, DeepSeek, Ollama and more — with context caching to cut cost and latency, and autonomy is configurable from full-auto down to fine-grained step-by-step control. It can also automatically debug terminal commands (builds, linters, tests) and browser apps when Chrome is installed.

The honest picture: Plandex pioneered ideas the whole CLI-agent category later absorbed, but its founder has acknowledged he couldn't compete head-on with Claude Code and moved on — so long-term momentum is uncertain even though the open-source core remains usable. The hosted Cloud tier runs about $45/month, and the terminal-first workflow has a steeper learning curve than IDE-native assistants.

Install via the one-line CLI installer from the Plandex docs; bring your own model provider API keys or use Plandex Cloud.