What AVIF actually is
AVIF (AV1 Image File Format) is an image format built on the AV1 video codec — the same underlying compression technology used for efficient video streaming. Applied to still images, it delivers roughly 50% smaller files than an equivalent-quality JPG, and it beats WebP too in most comparisons, which is why large websites and platforms have increasingly adopted it since the early 2020s.
Why it's suddenly everywhere
As browsers rolled out AV1 support and bandwidth costs stayed a priority for large websites, serving AVIF automatically to compatible browsers became standard practice for many major platforms. You never chose to download an AVIF file — the website simply served the smallest format your browser could display, and AVIF increasingly wins that contest.
Where it falls short
Compatibility. Recent versions of Windows, macOS, and mobile browsers handle AVIF fine, but a meaningful slice of older operating systems, desktop image editors, and upload forms still don't recognize it at all — which is exactly the situation that sends someone searching for how to open or convert an AVIF file in the first place.
AVIF vs WebP vs JPG
For pure file size at equal visual quality, AVIF generally wins, WebP is a close second, and JPG is the largest of the three. For compatibility, the ranking flips completely — JPG opens everywhere without exception, WebP is very broadly supported, and AVIF is the newest and least universally supported. As a practical rule: browsing the web, you'll increasingly receive AVIF without noticing; sharing or uploading a file yourself, JPG remains the safest choice.
What to do with an AVIF file you can't open
Converting it to JPG takes a few seconds and produces a file that opens in literally anything — old software, printers, upload forms, other people's devices. The conversion happens by decoding the AVIF's pixel data and re-encoding it as standard JPEG, so there's no meaningful quality loss for typical use.