pngcrush is a free and open-source command-line utility for
optimizing PNG image files. It reduces the size of the file losslessly;
that is, the resulting "crushed" image will have the same quality as the
source image.
Snaps are applications packaged with all their dependencies to run on all popular Linux distributions from a single build. They update automatically and roll back gracefully.
Snaps are discoverable and installable from the Snap Store, an app store with an audience of millions.