Check if gzip or Brotli is enabled. Show compression ratio. Free.
The HTTP Compression Tester requests a URL with Accept-Encoding: gzip, br and reports whether the response is compressed, which encoding was used, and the size before/after (compression ratio). Developers use it to confirm a server or CDN is compressing responses, to compare gzip vs Brotli, or to debug "content encoding" errors. Helps optimize transfer size.
You may see identity or no Content-Encoding; enable gzip or Brotli in your server or CDN config.
Brotli often gives a better ratio; support is widespread. Use both with appropriate Accept-Encoding.
Yes; many APIs support compression for JSON or large responses. Check the response headers.
DevTools may show decoded size; the tester shows transfer (encoded) vs decoded for ratio.
Compression and Range can interact; the tool typically tests a full response.