WebP

Compression methods and features

WebP is a RIFF-based container that stores image data encoded with VP8 (lossy) or VP8L (lossless). It supports 8‑bit colour, an 8‑bit alpha channel, animation, and metadata blocks for ICC colour profiles, Exif, and XMP.

Lossy mode uses block-based intra-frame predictive coding derived from VP8 video, while lossless mode uses dedicated transforms and entropy coding tailored for images. Alpha in lossy WebP is encoded losslessly, enabling high-quality transparency.

Compression modes and implications

Lossy WebP targets photographic content and usually produces smaller files than JPEG at similar visual quality. Lossless WebP often outperforms PNG for graphics with flat colours and transparency; near‑lossless settings can further reduce size with minimal perceptual change.

Animated WebP can replace GIF with better compression and colour fidelity, though animation increases decode work and memory usage. Choice of mode affects artefacts: lossy may introduce blocking or ringing; lossless preserves exact pixels at higher sizes.

Support status (desktop and mobile)

WebP is supported by current versions of all major browsers on desktop and mobile, including Chrome, Edge, Firefox, and Safari. Internet Explorer does not support WebP, and older browser versions may lack features such as animation.

Most image CDNs, build tools, and libraries can generate and serve WebP, and many platforms negotiate support via the Accept header. Native OS-level support exists across Android and modern versions of macOS and iOS.

Use cases

Use lossy WebP for photographs and complex imagery as a drop‑in alternative to JPEG. Use lossless WebP for UI assets and graphics with transparency as a smaller alternative to PNG, and animated WebP as a more efficient replacement for GIF in supported environments.

On the web, WebP is often delivered via the picture element with format fallbacks, or via CDN content negotiation. For archival workflows requiring exact preservation or vector scalability, PNG or SVG may be more appropriate.

Role in Core Web Vitals and rankings

By reducing image bytes and decode time, WebP can improve loading metrics such as Largest Contentful Paint (LCP) and First Contentful Paint (FCP). This supports better user experience and can help pass performance thresholds in Core Web Vitals.

Using WebP is not a direct ranking factor, but faster pages can influence SEO indirectly. Tools like Lighthouse and PageSpeed Insights flag “serve images in next‑gen formats,” and adopting WebP can resolve that audit.