Kornel

ffmpeg by default uses a fixed palette, making GIFs awfully dithered. Other tools aren't much better — they mostly generate a single not-so-great palette for the entire 256-color animation. gif.ski is different. It uses pngquant to make unique palette for every frame, and combines colors across frames, using thousands of colors in a GIF. The result is so nice you may not believe it's a GIF, but...

For years people have been asking me whether ImageOptim can work on Linux, and this is my answer to it. It's an HTTP API, so you can benefit from cutting-edge compressors without having to ./configure && make anything. It's also my research playground, so it has a new JPEG compressor that reduces color fringing (e.g. handles sharp red lines much better than usual encoders).

ImageOptim is lossless. There's a lossy companion app for it: http://pngmini.com