This is the 3rd launch from Cline. View more
Cline SDK
Launching today
Cline SDK is an open-source TypeScript agent runtime with plugin architecture, native subagents, MCP support, checkpointing, cron jobs, and web fetch.
For developers building custom coding agents or CLI tools.
Free Options
Launch Team
Cline just open-sourced the agent runtime that powers one of the most-used coding agents in the world.
What it is: @cline/sdk is a TypeScript agent runtime with a plugin architecture, designed to be embedded in any surface VS Code extensions, CLIs, desktop apps, Slack bots, or whatever you're building.
The problem with most agent frameworks is that the loop gets glued to the product surface. Cline had this same issue: the agent grew inside the VS Code extension, and eventually the runtime and the IDE wrapper were inseparable. The SDK is the result of pulling those two things apart: a stateless, reusable loop at the core, with a stateful runtime layer on top of it.
What makes it different: most coding agent runtimes aren't actually portable. They're designed to run inside one product. Cline SDK is explicitly built so sessions can move across surfaces, long-running work survives UI restarts, and the agent loop stays stateless regardless of where it's running. The plugin layer lets teams add domain-specific tools and observe lifecycle events without forking the runtime.
Key features:
Plugin architecture for registering tools, lifecycle hooks, and agent rules
Native subagents and multi-agent teams with built-in handoff and orchestration
Checkpointing, scheduled cron jobs, web fetch, and MCP connectors out of the box
Provider-agnostic: Anthropic, OpenAI, Google, AWS Bedrock, Mistral, LiteLLM, and OpenAI-compatible endpoints
Example apps included: Slack bot, VS Code extension, desktop app
Benefits:
Embed a production-grade agent loop without building the harness yourself
Swap models and providers via config, not code rewrites
Multi-agent workflows without a separate orchestration layer
Start small with individual packages, add the stateful runtime only when you need it
Who it's for: TypeScript developers building coding agents, internal dev tooling, or AI-powered CLI applications who want a stable, extensible runtime rather than a prompt wrapper.
The benchmark numbers on Terminal-Bench 2.0 will get attention, but what actually matters here is that Cline is releasing the same runtime they use internally as an open package. That's a different kind of credibility than a framework built specifically for public release.
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Plugin-based runtimes live or die on fault isolation. If a buggy tool crashes mid-session, does it kill the whole agent or is each plugin sandboxed? That's were most SDKs get sloppy.