When comparing Cortana vs Greenshot (for Windows), the Slant community recommends Greenshot (for Windows) for most people. In the question“What are the best power user tools for Windows?” Greenshot (for Windows) is ranked 10th while Cortana is ranked 74th. The most important reason people chose Greenshot (for Windows) is:
Greenshot is licensed under GPL with source code available on [BitBucket](https://bitbucket.org/greenshot/greenshot).
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Pros
Pro Can recognize music
You can ask Cortana what music is playing and she will attempt to identify it.
Pro Will let you know when artists you're interested in play in your area
Cortana monitors your Bing search history, social network actions, music played, etc to find out what are your favorite artists and will let you know if they plan to play in your area.
Pro Free and open source
Greenshot is licensed under GPL with source code available on BitBucket.
Pro Freezes screen when you capture
When you enter a capture mode, the screen content is preserved as it was when you started capturing.
Pro Allows annotating, highlighting and obfuscating screenshots
Pro Can capture an entire webpage
Instead of just capturing the visible portion of the page, this tool can capture all of the page in one image by scrolling through the page, taking images at set points and then stitching the images together.
Pro Can be quickly invoked with the print screen button
Pressing the print screen button will allow you to select the captured area.
Pro Selecting custom rectangle is the default
Easy to use selection tool with a magnifier to select only the part of the screen that you need.
Pro Classic UI design makes it easy to use.
Cons
Con Functionality is limited on non-Windows devices
While Cortana is available on Android and iOS, certain features on those operating systems are either limited or non-existant. For example, there's no hands-free voice activation on iOS, and on Android it's only available on the homescreen and nowhere else, etc.
Con Scrolling window capture is only working in Internet Explorer
Con This version only works on Windows, not Linux nor Mac
However, the same author now has a separate version of Greenshot for iOS, which is available (for a small fee) in the Mac App Store at https://itunes.apple.com/us/app/greenshot/id1103915944