AVIF Optimizer
Create AVIF images, the most efficient widely supported image format. AVIF files are often half the size of JPG at similar quality and support transparency and high dynamic range. Browsers cannot create AVIF on their own, so this tool runs the libavif encoder as WebAssembly in your browser: choose quality and encoder effort, optionally lossless, and convert a batch of images.
- Files stay on your device
- No sign-up
- Free to use
How to use AVIF Optimizer
- Drop images onto the page.
- Set the quality and encoder effort.
- Optionally choose lossless or a maximum size.
- Optimize and download the AVIF files.
AVIF Optimizer features
Real AVIF encoder
libavif compiled to WebAssembly.
Very small files
Often half the size of JPG.
Transparency
Alpha channel supported.
Lossless option
Exact pixels when needed.
Effort setting
Fast or smaller files.
Private
Converted in your browser; nothing is uploaded.
When to use AVIF Optimizer
- Large hero images and photography sites.
- Image-heavy shops and galleries.
- Reducing CDN and bandwidth costs.
- Testing AVIF before switching a site.
AVIF Optimizer FAQ
Why does encoding take a while?
AVIF achieves its savings with demanding compression. Large photos can take several seconds each; choose “Fast” effort or reduce the size to speed it up.
Which quality should I use?
AVIF quality numbers are not comparable to JPG. 50–65 suits most photos; use 70–80 for images with fine text or graphics.
Do browsers support AVIF?
Yes, current versions of Chrome, Edge, Firefox and Safari display AVIF. Provide a JPG or WebP fallback for very old browsers.
Why is a 3.5 MB download needed?
That is the encoder itself. It is loaded once, on first use, and cached by the browser.
Are my files uploaded?
No. Everything happens in your browser.
AVIF and how it is encoded here
AVIF stores still images using the AV1 video codec. AV1’s advanced prediction, larger and more flexible block sizes and better entropy coding preserve detail at bit rates where JPG shows blocks and WebP smears textures. For photographs, an AVIF file is frequently 40–50% smaller than a JPG of similar perceived quality.
Browsers can display AVIF but cannot create it through the usual canvas APIs. The optimizer therefore uses libavif, the reference AVIF library, compiled to WebAssembly by the Squoosh project and packaged by jSquash. It runs entirely in your browser: the image is decoded, optionally resized, and its pixels are passed to the encoder.
Encoder effort controls how hard the encoder searches for the best compression. Fast is several times quicker; the slower setting saves a few more percent. Lossless mode stores exact pixels, which is useful for graphics but produces larger files than lossy AVIF.
If the AVIF is not smaller than an AVIF you started with, the original is kept. For maximum compatibility, publish AVIF together with a WebP or JPG fallback using the HTML picture element.
Animated AVIF and HDR images are not created by this tool; it produces standard 8-bit still images, which is what websites use in practice.
Your images never leave your device.