Changelog

Today we are announcing the deprecation of several features from the Sandbox SDK. The SDK has grown and matured substantially since it first launched. As agent workflows have developed, we have shipped many new features and experiments so developers can easily integrate secure, isolated code execution into their workflows.

We want the SDK to continue providing a stable foundation for agentic workflows while we iterate quickly on the codebase. These deprecated features have either been superseded by newer capabilities or seen low adoption. Do not build new work on them. Migrate using the 2026 deprecation migration guide, or move to the Sandbox SDK 1.0 preview when you can.

In April 2026, we released the new RPC transport and deprecated the WebSocket transport. This setting governs how the sandbox container talks to the Workers ecosystem. The RPC transport removes the limitations of both the HTTP and WebSocket transports. As of this announcement, RPC is the recommended default. HTTP and WebSocket transports are deprecated and will not ship in future Sandbox SDK majors.

To migrate, update the SANDBOX_TRANSPORT variable to rpc or set the transport option when calling getSandbox(). For more information, refer to the transport configuration documentation.

The desktop feature ran a full Linux desktop inside the sandbox (display server, desktop environment, and VNC/noVNC) so agents and apps could drive a GUI with screenshots, mouse, and keyboard — the same computer-use shape other sandbox products expose for UI automation. Adoption stayed low, and we removed it in 0.10.2. If you need that capability again, you can build it on top of the sandbox with extensions rather than a built-in sandbox.desktop API.

We recently released support for Cloudflare Tunnel in the Sandbox SDK. This provides a robust API for exposing services running in your sandbox to the public internet. It fixes issues many were facing with local development and deployment to workers.dev domains. To migrate from exposePort() to tunnels, refer to the tunnels API documentation and the expose services guide.

By default, the exec() method in the Sandbox SDK maintains a default session across all calls, so a cd in one call is honored in the next. This convenience helped developers writing exec statements by hand, but confused agents and caused hard-to-trace bugs. As of 0.10.3, we have introduced the enableDefaultSession flag on the getSandbox() interface to turn this off. Default sessions as a concept — and the flag — will be removed in an upcoming release.

We recommend setting enableDefaultSession: false today and using the sandbox.createSession() API when you need the previous behavior.

We are also consolidating all APIs that buffer data to support streaming by default. This includes readFile, writeFile, and exec. The stream equivalents will be removed.

We are exploring moving non-core features like the code interpreter, terminal, and git APIs into helpers. These features will retain their existing APIs, so migration should be simple.

If you use any of these features on the current stable package, refer to the 2026 deprecation migration guide. Coding agents can use the sandbox-stable skill for stable-package work and that guide for cleanup (Agent setup · Cloudflare Skills ↗).

If you are moving to Sandbox SDK 1.0 (@next), use the 1.0 preview and Migrate guides instead — or the sandbox-migrate-to-next skill after installing Cloudflare Skills. New projects should prefer sandbox-next on @next.

For any questions, ask in the Cloudflare Developers Discord ↗.