Overview

image/webp is the media type for WebP images developed by Google. It supports both lossy and lossless compression plus alpha transparency and animation, and at equal quality produces smaller files than JPEG or PNG, benefiting web performance.

Details

WebP can replace the roles of JPEG (lossy photos), PNG (lossless with transparency), and GIF (animation) in one format, becoming a de facto standard for web optimization. Its lossy mode uses VP8 intra-frame coding and its lossless mode a separate algorithm. All major browsers support it today.

The serving pattern matters. The server performs content negotiation, checking whether the client's `Accept` header includes `image/webp` and returning WebP if so, otherwise JPEG/PNG. Since one URL then yields different formats per client, you must send `Vary: Accept` so caches do not get mixed up. Alternatively, a <picture> element lets the browser pick the best source directly.

Syntax

e.g. Content-Type: image/webp

File extensions

Notes

• When switching formats based on Accept, always send Vary: Accept so CDNs/proxies do not cache the wrong format.
• AVIF often compresses better, so a three-tier strategy (AVIF → WebP → JPEG) with WebP as an AVIF fallback is common.
• Already-compressed binary, so transport gzip provides no benefit.

Related types

Related headers