About ResizeImageOnline
ResizeImageOnline is a small set of image tools that run entirely in your browser: compress, resize and convert JPG, PNG, WebP and AVIF files without sending them anywhere.
How it works
When you add a picture, the browser reads it from your disk. A background worker decodes it, applies the size you asked for and encodes it again with a WebAssembly build of a well-known codec: mozjpeg for JPG, libwebp for WebP, libavif for AVIF, and oxipng for PNG. The result stays in memory until you download it or close the tab.
What it does not do
There is no crop, rotate or collage tool, no editing of layers, and no cloud storage. Animated GIF and PNG files are not supported. Very large images can fail on devices with little memory.
Open source parts
The codecs come from Squoosh and the jSquash packages, and ZIP files are written with fflate. Version numbers are listed in the licenses file.