CLI
ImageMagick
ImageMagick is one of the most popular open-source software mainly for command-line image editing and manipulation.
FFmpeg
FFmpeg is mainly a video/audio processing tool, but it is useful for images too.
Online Tools
- AVIF and WebP: Use https://convertimg.online to convert from any image format to AVIF and WebP.
- PNG: For the rare cases when you can’t use WebP or AVIF for some reason, utilize https://tinypng.com/ to optimize PNG files effectively.