PNG to AVIF converter

This is the most aggressive size reduction available for a web graphic. PNG stores everything exactly and pays for it; AVIF compresses hard while keeping the alpha channel that made PNG necessary in the first place. For a large illustration, a photographic background or an artwork-heavy page, the saving is often an order of magnitude. For a small flat icon it may be nothing at all — which is worth knowing before you convert a folder of them.

When you actually need this conversion

• A large PNG illustration or photographic export is the heaviest asset on a page.
• You need transparency and the smallest possible file, and the destination is a browser.
• You are replacing a set of hero images or backgrounds where the download happens on every visit.

What to watch out for

• Lossy AVIF will soften fine lines and small text. For a diagram, a chart or a UI screenshot, keep PNG or use lossless AVIF and check the result.
• Small icons often do not shrink, and sometimes grow. Below roughly 100×100 pixels the format overhead outweighs the compression.
• Encoding is slow, especially for large images. This is a one-off cost, not something to run on every page load.

PNG and AVIF, side by side

Excellent for illustrations and interface graphics with flat colour, where AVIF’s handling of gradients avoids the banding JPEG produces. Transparency is preserved.

How the conversion works here

Your file is decoded in a Web Worker inside this browser tab — by the browser's own image pipeline where it can, and by a WebAssembly build of libheif or libavif where it cannot. The decoded pixels are then re-encoded with libavif, the same encoder Squoosh uses.

All of that happens on the processor in front of you. There is no upload step, no queue and no server, which is why there is no size cap, no daily allowance and no paid tier — and why the whole thing keeps working with the network switched off.

Doing more than one thing

Most people converting a format also need it smaller or a different size. The result screen hands your converted files straight to the compressor or the resizer in one click — no second download, no re-selecting files. If you need several formats, the general converter lets you pick the output each time.