Pi

Earendil · Terminal & CLI Agents · Updated Aug 12, 2026

Pi is a minimal, highly extensible terminal-based coding agent harness that prioritizes developer control over opinionated workflows. It features a tree-structured interaction model and an extensive TypeScript-based plugin system that allows users to add custom capabilities like sub-agents or planning tools as needed.

Recent Updates

Recent releases include Claude Opus 5 support, constrained tool sampling, OAuth login support, and improved AWS Bedrock integration.

As of Aug 12, 2026

Key Features

Tree-structured session history for branching and non-linear exploration
Radically minimal four-tool core (read, write, edit, bash)
Support for 15+ providers and hundreds of LLM models with mid-session switching
Extensible via TypeScript extensions, skills, prompt templates, and themes
Four operating modes: interactive, print/JSON, RPC, and SDK

Who It's For

✓ Best For

CLI power users and developers who want full control over their AI coding workflow, need custom integrations, or prefer avoiding vendor lock-in.

✗ Not Ideal For

Beginners seeking an out-of-the-box experience, teams requiring enterprise compliance/auditing, or developers who rely heavily on IDE-integrated GUIs.

Pricing

Free

Free and open-source (MIT license); users pay only for their own third-party API usage (e.g., Anthropic, OpenAI) or run free local models via Ollama.

Verdict

Pi is the premier 'do-it-yourself' coding harness for developers who want a fast, hackable, and model-agnostic terminal agent, though its lack of out-of-the-box features presents a steep learning curve for the uninitiated.