Workbench / Interactive programming

Browser code playground

Edit an example, run assertions, inspect the result, and try a broken case. No remote execution or login.

Run editable JavaScript and assertions

JavaScript only in this version. It runs in an opaque-origin sandboxed iframe with network, forms and navigation blocked by CSP and sandboxing. This is not a general-purpose secure compute service; never paste private code or credentials.

ExampleJavaScript editor (maximum 4,000 characters)

Choose Run code to execute inside an isolated browser frame.

2-second best-effort timeout; heavy loops may still impact browser performance. No code is uploaded or retained.