Overview

image/avif is the media type for the AV1 Image File Format, applying the AV1 video codec's intra-frame technology to still images. At equal quality it produces smaller files than JPEG or WebP, drawing attention as a next-generation web image format.

Details

AVIF supports HDR, wide color gamut, 10/12-bit depth, alpha transparency, and animation, and its compression efficiency is markedly better than JPEG especially at low bitrates. Most modern browsers support it, but coverage of older environments is narrower than WebP, so the standard pattern negotiates AVIF when `Accept: image/avif` is present and falls back to WebP/JPEG otherwise — again guarded by `Vary: Accept`.

The trade-off is encoding cost. AVIF encodes much more slowly and CPU-heavily than JPEG/WebP, so it fits pre-generation at build time or in a CDN image pipeline better than real-time conversion of many images. Listing AVIF → WebP → JPEG sources in a <picture> element to let the browser pick a supported format is widely used.

Syntax

e.g. Content-Type: image/avif

File extensions

Notes

• When negotiating on Accept, always send Vary: Accept so a CDN does not cache AVIF for unsupported browsers.
• Encoding is slow and heavy, so pre-generation (build step or image CDN) is more practical than real-time conversion.
• Provide an AVIF → WebP → JPEG chain via <picture> for older-browser fallback. Already compressed, so transport gzip is pointless.

Related types

Related headers