Compression and Concatenation on the Web

When sending data to browsers, compression reduces file sizes but requires tradeoffs between compression ratio and speed—static assets can use expensive compression done once at build time, while dynamic responses need faster compression to avoid latency. The three major compression formats in use today are gzip (dominant in non-CDN traffic), brotli (now plurality in CDN traffic since 2017), and zstd (newly available on all major platforms in 2025), with brotli expected to gain further adoption. The article explores how these compression formats, particularly gzip, handle file concatenation and the technical challenges that arise when combining compressed files.