SHA1Sum

SHA1Sum is a command-line application that enables users to calculate and compare the SHA1 checksums between two files. It comes packed with few features that can be quickly learned.
While most users prefer graphical interfaces with an intuitive structure for performing a simple task, some of them would rather work with a Command Prompt dialog, since a few inputted lines are usually enough to get the job done in no time.
Installation is not required, so you can drop the program files somewhere on the hard disk and call SHA1Sum's process from a Command Prompt dialog.
It is also possible to save SHA1Sum to a USB flash disk or similar storage unit, in order to run it on any machine without prior installers.
What's more, the Windows registry does not get updated with new entries, and files are not left behind on the HDD after removing the tool.
You can compute an SHA1 signature, save it to an external file, as well as check the SHA1 checksm of an existing file and compare it with another. Note that the processed files must be placed in the same directory as SHA1Sum.
As expected, the application has minimal impact on system performance, running on a very low quantity of CPU and RAM. It has a good response time and quickly finishes a task. No error dialogs were shown in our tests, and the app did not hang or crash.
All in all, SHA1Sum offers a simple method for calculating and comparing SHA1 signatures with minimum effort.