Greetings, friends! Sometimes, after downloading a program from the internet, we proceed with the installation, and surprise! We can't run it because Windows throws up an error message saying the file has an unknown format or is damaged ( corrupted ). Then the question arises: what happened? Was the download corrupted along the way? Is the program actually damaged by its developer?
The truth is that there is something very important you should know about the programs or files you download from the Internet: each one has something like its own "digital fingerprint" or "license plate," if we make an analogy, which consists of an algorithm that you see as a series of unique numbers and letters ; this is a hash in computer terms, the most common being SHA1 and MD5.
What is a hash for?
The main goal is to verify that the file hasn't been corrupted or altered during download. You'll usually find that the developer's website provides the program's hash code alongside the download link. Knowing the original hash code, you can compare it to the one in the downloaded file. This way, you can be sure the file downloaded correctly, check its status, and see beforehand if it will work properly, if it's not infected, or if it hasn't been modified during its journey to your PC—all of which is synonymous with security.
How to verify a downloaded file?
It's so easy! It won't take you even 5 seconds and will save you a lot of headaches. At VidaBytes, we've compiled 4 free tools for calculating hashes ; they're practical and intuitive, so anyone can use them 😉
We present each of them in action, the hash algorithm of the MultiHasher application (which we will also comment on) was used as an example to check the file downloaded from the official page with the original hash.
After installation, it integrates with Windows Explorer—hence the extension name. Simply right-click, go to the " Checksum " tab in Properties, and you'll get the hash code you're going to compare. It's that easy!
HashCheck Shell Extension weighs only 85 KB, is free and compatible with Windows from version XP onwards.
2.hashtab
Another fantastic browser extension, multilingual (available in Spanish) and very complete. This time, the official website provides its hash codes (signatures), so we proceeded to test it by comparing them with its own tool. It works like a charm 
It is 887 KB in size, free for personal use, and available for Windows and Mac.
3. MultiHasher
Probably the most comprehensive hash calculator available, and it's completely free. You can drag and drop files or upload them to its interface, and MultiHasher will calculate up to six different hash signatures (CRC32, MD5, SHA-1, SHA-256, SHA-384, SHA-512) using the most efficient techniques.
The hash signatures of this tool are also provided on the official site and the result of the comparison can be seen in the capture with the same tool, which by the way is available in a portable and installable, multilanguage version.
4. HashMyFiles
I'm a self-proclaimed die-hard fan of NirSoft utilities and I couldn't leave out HashMyFiles . Needless to say, it's an excellent program: easy to use, free, portable, and available in several languages, right? 😉
For Linux and Mac users , the Genbeta blog also discusses the topic and explains how to verify hashes using the console ; I recommend reading it.
I hope that this information is useful to you and that you put it into practice often to avoid unpleasant surprises. If you know and want to discuss other alternatives, they will be welcome 