Https://tools.pdf24.org/en/ This tools is not open sourc, but it’s free. - Source: Hacker News / 6 months ago

PDF24 provides a suite of user-friendly tools covering virtually every aspect of PDF manipulation. The tools run directly from your web browser, are accessible on any device with an internet connection, and require no software installation. KameNoOtoko raves, "PDF24 is amazing!". Source: 7 months ago

Free PDF solutions for all PDF problems - Anything you want to do with a PDF. I like this one. (One of My Favorites). Source: 11 months ago

I've been using https://tools.pdf24.org/en/ for a while now, pretty good offering there. - Source: Hacker News / over 1 year ago

I also use Caesium Image Compressor on my ROMs and Themes folder to reduce their size and improve the RG35XX's responsiveness. Source: about 1 year 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: over 1 year ago

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