PI

Pi provides an AI coding agent and toolkit for developers working in the terminal or building their own agent applications. Its coding CLI can read and edit files, execute shell commands, switch models mid-session, and resume or branch conversations. The toolkit separates a unified model-provider API, an agent runtime with tool execution and state management, and a terminal UI library. Developers can connect hosted providers or use local models through llama.cpp.

Created by Mario Zechner, Pi emphasizes a small, extensible foundation: its default four tools and system prompt together occupy fewer than 1,000 tokens. Its engineering includes context handoffs between model providers and tool results that separate model-facing content from UI presentation. Extensions let developers add workflows around that foundation; Shopify’s pi-autoresearch extension runs optimization experiments against measurable targets.

Earendil acquired Pi in 2026, with Zechner joining as a shareholder and remaining at the helm. Earendil was founded in 2025 by Armin Ronacher and Colin Daymond Hanna, who share Pi’s governance with Zechner. Pi’s core remains MIT-licensed, allowing developers to modify it and build commercial products on top. Its role extends beyond coding sessions: Pi powers the agent inside OpenClaw, and Earendil builds its own products on the toolkit.