Playground

The playground runs the same Rust engine as the CLI, compiled to WebAssembly. Paste code on the left and the output appears on the right. Nothing is uploaded. Your code stays in the browser tab.

The header shows the engine version and commit. A shared link tells the reader exactly which build produced the output.

Decompile

The default mode. Output updates as you type or change a setting.

• Example loads a sample: Babel output, TypeScript output, Terser output, or a CommonJS interop module.
• Level is the same minimal / standard / aggressive choice as the CLI. See Rewrite levels.
• Formatter runs a formatting pass after decompilation. It is on by default in the playground and off by default in the CLI.

Warnings from the engine appear under the output.

Mapping

Turn on Mapping and every output line is colored by the input line it came from. Hover a line on either side to highlight its counterpart. The percentage next to the switch shows how much of the output has a mapping.

This is the source map the CLI writes with --emit-source-map, drawn instead of saved. The formatter is turned off while Mapping is on. See Source maps.

Compile & Restore

Write modern source on the left. A real transpiler compiles it in your browser, and Wakaru restores the result. You see all three: your source, the compiled output, and what Wakaru gets back.

• Producer picks the transpiler: Babel, SWC, or esbuild. Each one targets an older browser, so async/await, classes, spread, optional chaining, and JSX all get compiled down.
• The Diff tab in the output pane compares Wakaru's output against your original source. That is the quickest way to see what a round trip keeps and what it loses.

Vue SFC

An experimental switch. When recovery succeeds, a Vue SFC tab appears next to the JavaScript output. When it does not, the JavaScript output stays as is. See Vue SFC for what recovery covers.

Share

Share copies a link to your clipboard. The code and every setting are compressed into the URL fragment, the part after #. Browsers do not send the fragment to any server, so the link works without a backend and your code still stays private. Very large inputs cannot fit in a URL, and the button says so.

When to use the CLI instead

The playground handles one file at a time. Reach for the CLI when you need to:

• Unpack a bundle into modules
• Feed in a directory, or an entry plus its chunks
• Apply an input source map with --source-map
• Get --json output for scripts or agents
• Work on inputs too large for a browser tab

See Install to get the CLI.