AVIF cleared: one fallback can go

The AV1 image format. Chrome has decoded it since 2020; Edge completed the core set on January 25, 2024, and the 30-month clock ran out on July 25. If your images ship as a three-format stack, AVIF on top, WebP in the middle, JPEG at the floor, the middle is now dead weight.

Delete: the WebP sources in your <picture> elements, and the encode step that produces them.

−<source srcset="chart.avif" type="image/avif">
−<source srcset="chart.webp" type="image/webp">
−<img src="chart.jpg" alt="Monthly revenue">

+<source srcset="chart.avif" type="image/avif">
+<img src="chart.jpg" alt="Monthly revenue">

A browser takes the first source whose type it supports, and every browser in the core set now takes the AVIF. The browsers still outside the set never reached the WebP for its format; they needed a floor they could render, and that is the JPEG’s job. What the WebP bought them was bytes: without it they download the same picture, heavier. That is the whole cost of the deletion, and it falls on a shrinking audience.

The floor stays. AVIF sits at about 93% of global traffic on caniuse’s counters, so a bare .avif in src with no fallback is a broken image for about one visitor in fifteen: desktop Safari before 16.4, iOS before 16.1, and every browser too old to have met the format. A missing image does not degrade, it is simply absent. Delete the middle of the stack, never the bottom.

Most sites never built this stack. In the HTTP Archive’s 2024 almanac, about one image in eight was a WebP and about one in a hundred an AVIF, and a <picture> that switches on format appeared on a few pages in a hundred. Search your templates for type="image/webp": if nothing comes back, or the floor under your sources is itself a .webp, there is no middle to delete and nothing to do this month.

One number needed a look before this verdict could ship. webstatus.dev scores stable Firefox at 0 on AVIF’s tests. The suite behind that number is two rendering tests, and ordinary still-image decoding is in neither: one advances an animated AVIF to its second frame, the other renders a file carrying a progressive-rendering flag. Firefox currently fails both. For a static image stack, the deletion above, they say nothing. If you ship animated or progressively encoded AVIF, test those files in Firefox before leaning on them.