Performance Tools
Content Encoding Checker
Check which content encoding (gzip, br, deflate, or identity) a website uses.
Enter a domain to check which content encoding it uses.
JustChecker tracks your website's performance signals continuously.
Frequently Asked Questions
It means no compression is being applied at all - the response is sent exactly as-is, which is the least efficient option for text-based content and worth investigating if seen on a page that should be compressed.
Those tools check specifically for one compression method each; this tool reports whichever encoding is actually being used right now (gzip, br, deflate, or none), giving a single, direct answer rather than checking each possibility separately.
Deflate is an older, less commonly used compression format with less consistent client support than GZIP - it's relatively rare to see intentionally chosen over GZIP or Brotli on a modern, well-configured server.
Yes - a server might compress HTML/CSS/JS responses while correctly leaving already-compressed formats like JPEG images uncompressed, since compressing an already-compressed file provides negligible benefit and wastes CPU time.
The browser sends an Accept-Encoding header listing what it supports; the server then chooses the best mutually-supported option to actually use - it's a negotiation, not a purely server-side or purely client-side decision.