When comparing ShiftIt vs Spectacle, the Slant community recommends Spectacle for most people. In the question“What are the best power user tools for macOS?” Spectacle is ranked 37th while ShiftIt is ranked 46th. The most important reason people chose Spectacle is:
Spectacle is licensed under MIT with source code available on [GitHub](https://github.com/eczarny/spectacle).
Ranked in these QuestionsQuestion Ranking
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 Open source
ShiftIt is very straight-forward to use for most frequent usages.
Pro Free and open source
Spectacle is licensed under MIT with source code available on GitHub.
Pro Simple hotkeys
Spectacle offers easy-to-remember preset hotkeys.
All windows in Spectacle can be controlled with keyboard shortcuts, so no mouse is needed. This makes for a fast way to control windows.
Pro Low footprint
Spectacle only uses up 18-19 MB of RAM, which means there is not much overhead by using this app.
Pro Great UX
Spectacle is easy to use and configure. It's plug and play.
Pro Multi-monitor support
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 Breaks on macOS High Sierra / Chrome or Firefox
Doesn't support side by side windows.
Con Impossible to add new functions
While keyboard shortcuts can be changed for the available actions, there is no way to add custom actions which in turn limits the functionality of the app.
Con Limited window sizing capabilities
You can use 1/2 of the screen vertically and horizontally (divide into 4 parts). You can also use the screen in thirds too, but only the left and right third: you can't use the 1/3 in the center. There is no way to do a more granular distribution.
Con Not maintained
The software is free, but no longer seems to be maintained.
Con Doesn't work with any Adobe products
There are some apps like Adobe Reader that do not work with Spectacle. Basically, any app with a heavily customized UI that breaks OS X accessibility will not work correctly under Spectacle.