How to Fix a Unity WebGL Build Too Large Without Brotli Compression

Unity WebGL builds are dominated by the WebAssembly and data files. Brotli compresses them substantially better than Gzip, but only if the server advertises the encoding. Without correct headers the browser either fails to decompress or downloads uncompressed.

How to fix it

1. Enable Brotli in Player Settings

Under Player Settings > Publishing Settings, set Compression Format to Brotli and rebuild. Unity emits .br files for the build artifacts.

2. Serve the right headers

Configure your host to return Content-Encoding: br and the correct Content-Type for the .br files. On hosts that cannot set headers, enable Unity's Decompression Fallback instead.

3. Strip and disable extras

Combine Brotli with code stripping and disabling the Development Build, exceptions, and the data caching that inflate transfer size for the smallest download.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every HTML5 error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.