Re-encode JPG photos as AVIF for markedly lighter files. Everything runs in this tab, and the encoder loads once on your first conversion.
Photos dominate the byte count of most websites, and JPG — for all its ubiquity — is a compression scheme from the early nineties. AVIF applies far newer techniques to the same job and generally delivers a visibly similar photo in substantially fewer bytes. If you are preparing hero images, product shots, or a gallery for the web, converting the JPGs to AVIF is one of the few changes that reduces load time without touching a line of layout or code.
This is the trade-off to be clear about. Your JPG has already discarded detail — that is how it got small. Converting it to AVIF runs the surviving pixels through a second lossy encoder, so a little more quality goes on this pass, and no encoder can put back what the JPG threw away. In practice a high-quality AVIF made from a decent JPG is hard to tell from its source on screen. The rule that keeps you safe is simple: convert copies and keep the originals, especially if the photos might be edited or printed later.
AVIF encoding runs in WebAssembly, and the encoder — about 3.4 MB — downloads once on your first conversion and is cached from then on. It is also the slowest format this converter produces, so a hundred-photo batch takes real minutes rather than seconds. Three images encode in parallel and each reports its old and new size as it finishes. None of them leave your computer: there is no upload step, no account, no watermark, and no daily limit on how much you convert.
It depends on the photo and on how heavily the original JPG was compressed. The tool prints the before and after size for every file, so you can judge the saving rather than trust an average.
At normal viewing sizes, rarely. The output is encoded at a high quality setting — though it is a second lossy pass, so close inspection of an already heavily compressed JPG can reveal differences.
The WebAssembly AVIF encoder has to be fetched and compiled before any image can be written. That happens once; afterwards your browser serves it from cache.
On the web, yes — all current browsers display AVIF. Desktop software and upload forms are patchier, so keep a JPG on hand for anything outside a browser.
No. Decoding and encoding both happen in a Web Worker inside this page, so the images stay on your device from drop to download.