When comparing ShiftIt vs ImageOptim, the Slant community recommends ImageOptim for most people. In the question“What are the best power user tools for macOS?” ImageOptim is ranked 8th while ShiftIt is ranked 46th. The most important reason people chose ImageOptim is:
Great for compressing images for web usage or saving harddrive space.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Easy to configure
ShiftIt is configured through a simple UI where you simply press the hotkeys you wish to map to a certain action.
Pro Free
Pro Intuitive
ShiftIt is very straight-forward to use for most frequent usages.
Pro Open source
Pro Configuration can be committed to your personal dotfiles repository
Configuration winds up living in .hammerspoon/init.lua and .hammerspoon/Spoons/ShiftIt.lua. Very easy to track configuration changes.
Pro Losslessly compresses PNG, GIF, and JPEG images
Great for compressing images for web usage or saving harddrive space.
Pro Fast & Simple
Pro Simple drag'n' drop interface
Simply drag images (or folders) into the window.
Pro Tries several different image optimizers before picking the best one
Pro Edits files in place
It does edit files in place, overwriting the original. This is exactly what I want, so I love it, but it's good to know beforehand.
Pro Can handle PNG, GIF, and JPEG images
Great for compressing images for web usage or saving harddrive space.
Cons
Con A little slow
Similar to Spectacle, but it has a few more features, such as being able to pick the size adjustment increments. Spectacle was a little faster, though. Repeated size changes or moves in succession can cause it to wait for it to complete.
Con Imprecise when readjusting sizes
Con Doesn't support moving windows between workspaces
There's no way to move a window to a different workspace with hotkeys in ShiftIt.
Con Compression algorithm not as good as counterparts
Con Cannot abort an optimization
Optimization can run for a long time. Sometimes it reaches 20% quickly and then spend a long time to attain 21.2%. But you cannot interrupt the process.