Actual encoding
Use the final Content-Encoding response instead of a configuration claim.
Gzip / Brotli Compression Checker
Gzip / Brotli Compression Checker
Inspect the actual Content-Encoding, transferred size and decoded size.
Enter a website URL to start
Web transfer-size optimization
What are Gzip and Brotli?
HTTP compression reduces transfer bytes for HTML, CSS, JavaScript, JSON, XML and SVG. Clients advertise algorithms with Accept-Encoding and servers return the choice in Content-Encoding.
Brotli often compresses text better; Gzip has broad compatibility. Images and video are already compressed and should not usually be recompressed.
What is checked
Transferred and decoded bytes
Show compressed bytes read and bytes after bounded decoding.
Measured savings
Calculate savings from this response rather than a fixed estimate.
Why test the real response?
A control panel can say compression is enabled while a hostname, route, proxy or MIME configuration still returns an uncompressed page.
Reduce page transfer
Shrink HTML and scripts for faster loading on constrained networks.
Find proxy differences
Verify what the CDN, reverse proxy and origin actually return.
Measure current savings
Compare real transferred and decoded body bytes.
How does the compression checker work?
The tool sends Accept-Encoding: br, gzip, deflate and reads the final response once within strict size limits.
- 01
Advertise support
Request Brotli, Gzip and Deflate like a modern browser.
- 02
Read the encoding
Use final Content-Encoding as the source of truth.
- 03
Decode within limits
Apply compressed and decoded byte caps to prevent oversized payloads.
- 04
Calculate and advise
Show both sizes, savings and missing compression.
Gzip and Brotli FAQ
Is Brotli always faster than Gzip?
It often compresses better, but compression level, dynamic CPU cost and caching affect total performance.
Why can Content-Length differ from transferred bytes?
Chunking, read limits, proxy handling and framing can create differences.
Should images use Gzip?
JPEG, PNG, WebP, AVIF and video are already compressed and gain little.
Are results stored?
No. Results remain on the page and use only short server caching.
Related web technology tools
Continue with cache policy, HTTP protocols and CDN delivery.