OptiPNG VS Caesium Image Compressor

Did you compare to PNG crush and optipng? Those are what I used to use because they're easily installable Linux/brew packages. Source: about 1 year ago

Assuming your frames are PNG files, you could use a lossless optimizer like optipng to try if their size can be reduced. I prefer oxipng, which is faster and multithreaded, and seems to have more active development. Source: over 2 years ago

I also use Caesium Image Compressor on my ROMs and Themes folder to reduce their size and improve the RG35XX's responsiveness. Source: 12 months ago

If you want further compression you could check out Caesium Image Compressor which is free (and I'm not affiliated with it incidentally, I just like it). Source: about 1 year ago

Try an image compression tool, this one is free and open source: https://saerasoft.com/caesium/. Source: about 1 year ago

Caesium Image Compressor can do the job and it is easy to use. There is also imagemagick which is basically the swiss-knife for image editing, but based on you having looked for websites first, I assume you don't look for a commandline tool (imagemagick is a commandline tool). Source: almost 2 years ago

I can recommend Caesium , a utility (Windows, MAC version in Alpha test) to remove all EXIF, metadata etc which will reduce your JPG in size quite a lot without using higher JPG-compression (lower quality). Source: almost 3 years ago