From the Store description:
Check the integrity of your files on desktop and phone.
File Hasher is a hash calculator that computes MD5, SHA1 and SHA256 checksums of any file, while allowing to easily compare those against a reference value.
Perfect for making sure a file has not been corrupted or tampered with and requiring no permissions, it is the perfect tool for the security-conscious.
There's not that much to see, but here's File Hasher UWP in action:
An extra field at the bottom is marked as 'Check'. The idea is that the expected result of one of the hashes is listed independently somewhere (often on a web page) and you can then copy and paste this into the last field. The application then checks whether this is identical to one of the calculated hashes and puts up a little tick mark if it is. Given that the hashes are long and very complex, this saves time and possible human error and is a nice touch.
You can grab this small UWP app for free here. For Windows 10 Mobile or, indeed, for Desktop/laptop etc.