Chrome silently drops half your page when you concatenate gzip files

Compression and Concatenation on the Web

Compression reduces bytes sent to the browser, but joining pre-compressed files is trickier than it seems. gzip is famously concatenable, yet curl errors out and Chrome silently discards the second part. Brotli's reference implementation doesn't support concatenation at all, though Dropbox's rust-brotli adds appendable and catable flags. zstd, built for concatenation from the start, works seamlessly with both curl and Chrome.