Radical Image Optimization Tool (RIOT) is a free image optimizer that will let you to visually adjust compression parameters.
PNGGauntlet
Free
PNGGauntlet is a PNG compression app for Windows.
OptiPNG
Open Source
OptiPNG is a PNG optimizer that recompresses image files to a smaller size, without losing any information.
ImageOptim
Open Source
ImageOptim makes images load faster. Removes bloated metadata. Saves disk space & bandwidth by compressing images without losing quality.
JPEGmini
Commercial
JPEGmini is a photo optimization software.
Compare optimus.io with alternatives
Compare RIOT - Radical Image Optimization Tool and optimus.io and decide which is most suitable for you.
Compare ImageOptim and optimus.io and decide which is most suitable for you.
Compare PNGGauntlet and optimus.io and decide which is most suitable for you.
Compare JPEGmini and optimus.io and decide which is most suitable for you.