Why browser-based?
Most online image converters work the same way: you upload your file to someone's server, it is processed there, and you download the result. That costs you time on a slow connection, and it means a stranger's computer has a copy of your photo.
PixSquash takes a different route. Every tool on this site is a small program that your browser downloads once and runs locally. Your image is decoded, edited and re-encoded by your own device - the same silicon that took the photo in the first place. Nothing is transmitted, so there is no upload wait, no server queue, and no privacy trade-off.
What can you do here?
Three things, each with a dedicated page for the exact job you are trying to finish: change an image from one format to another, compress it down to a specific file-size limit, and resize it to the exact pixel dimensions a platform expects. If you are not sure which one you need, start from the three collections above.