Here you can execute and debug – inside your browser – contracts meant to run on the NEAR protocol. Use the browser built-in developer tools (often available via Ctrl/Cmd ShiftI): log messages and errors will show up in the console and you can use the debugger to step through the contract code.
The debugging experience will differ between browsers. For instance Chromium supports DWARF
debug info. Contracts built from Rust source will embed such debug info into the
.wasm file, as long as debug info is enabled. This would then allow
debugging Rust code and not the underlying WebAssembly!
window.contract in the console will allow you to explore some specifics of the
contract runtime throughout the execution of the contract.