Headers

Headers #

WebP Server Go returns the following response headers:

  • vary

    • Image response example: Accept
    • Negotiated image responses use Vary: Accept, allowing compatible shared caches to keep separate variants selected from the request’s Accept header.
    • The CDN must honor Vary or include Accept in its cache key. See Use with CDN.

  • etag

    • Example: W/"87328-49BF2BCE"
    • This header is produced by W/"<content length>-<CRC Checksum of the file>"

  • x-compression-rate

    • Example: 0.87
    • This header is produced by size(returned_image)/size(original_image). If the optimized image is larger than the original, WebP Server Go can return the smaller original image instead.