image/webp

Google's do-everything web image — lossy, lossless, alpha, and animation in one format — that shipped for over a decade before finally getting a defining RFC in 2024. Send it as the modern default when every target browser supports it, keeping JPEG or PNG behind content negotiation for stragglers. It lives inside a RIFF container, so the first four bytes read RIFF like a WAV or AVI file; the bytes that actually identify WebP sit at offset 8.

Defined by RFC 9649 · IANA registration. Registry facts from the IANA media-types registry via mime-db.