Yep, it is! You can find the sources on GitLab[0]. The compression is done using brotli-wasm[1].
The entry point to the compression is the syncCompress[2] function, which converts the data to UTF-8, adds the needed header bytes, and then compresses using brotli-wasm. Decompression is done in a streaming way in streamDecompress[3]. This is to avoid zip bomb attacks, where even a short URL could decompress to gigabytes of data, locking the browser. Thankfully brotli-wasm had streaming decompression builtin, I just had to write the wrapper code to update the text content and the status bar in the UI.
You can find the brotli-wasm code I'm using in the vendor folder[4], there is a JS wrapper and then the WASM code (both are straight from brotli-wasm).
