Pi

A minimal, customizable A.I. coding agent harness you run from your terminal

Visit PiPricing not listed

Pi is a minimal agent harness. In plain words, it's a small program that lets an A.I. model work on tasks for you, and it's built so you can reshape it to fit how you work. The pages list Earendil Inc. & Contributors and an MIT License.

You can customize Pi with extensions, skills, prompt templates and themes, then bundle them as packages and share them through npm or git. Pi works with 15+ providers and hundreds of models, including Anthropic, OpenAI, Google and Ollama. You can switch models mid-session. It has four modes: interactive, print/JSON, RPC and SDK. You install it with a one-line command, or with npm, pnpm or bun. It skips features like sub-agents and plan mode, but you can ask Pi to build them or install a package.

What it does

Extend it with extensions, skills, prompt templates and themessource: pi.dev
Works with many model providers and lets you switch mid-sessionsource: pi.dev
Sessions are saved as trees you can branch and revisitsource: pi.dev
Share a session as HTML or a GitHub gist linksource: pi.dev
Send steering or follow-up messages while the agent workssource: pi.dev
Built-in MCP support, with Codemode for composing tool calls in a sandboxsource: pi.dev
Embed Pi in your own apps with the SDKsource: pi.dev

Our take (opinion)

Best for

💻 Developers who are comfortable in a terminal and want to shape their own A.I. coding tool
🔧 Tinkerers who like building extensions instead of accepting fixed features

Watch out for

⚠️ It's a command-line tool, so it may feel tricky for beginners
Pricing isn't listed on the pages, and you'll likely need your own model provider access via API keys or OAuth
Sub-agents, plan mode and permission popups aren't built in, so you'll need to add them yourself