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Cline open-sourced their agent SDK (npm package @cline/sdk) and announced it on…

2026-05-13 · 15:39 UTC ·@dr_cintas ·1 min read

Brief

Cline released a new open-source agent SDK (npm @cline/sdk) on 2026-05-13, rebuilding their harness from the ground up. The TypeScript API exposes file editing, terminal commands, browser automation, and MCP servers, is ACP-compatible, and runs the identical engine used in Cline's VS Code extension, CLI, JetBrains plugin, and Kanban board.

Why it matters

Cline open-sourced their agent SDK (npm package @cline/sdk) and announced it on 2026-05-13; the repo is stated as 100% open source.

Key details

  • The SDK is a rebuilt-from-scratch TypeScript harness exposing file editing, terminal commands, browser control, and MCP servers, is ACP-compatible (Agent Client Protocol), and uses the same engine powering Cline's VS Code extension, CLI, JetBrains plugin, and Kanban board — built from lessons since their 2024 coding agent.
Source evidence

Cline just open-sourced their agent SDK 🤯

They spent the last few months rewriting their entire harness from the ground up.

What you get:

→ File editing, terminal commands, browser use, and MCP servers through a TypeScript API
→ ACP-compatible (Agent Client Protocol)
→ The exact same engine running their VS Code extension, CLI, JetBrains plugin, and Kanban board

npm i @cline/sdk

100% Open Source.

Video

Cline (@cline)

Introducing the Cline SDK. We rebuilt the Cline harness for our extension and CLI from scratch using all the lessons learned since creating one of the world's first coding agents in 2024, and are open sourcing it for others to build with today.

npm i @​cline/sdk

🧵

Video

— https://nitter.net/cline/status/2054580767779700775#m