# What is a file Hash and why is it vital for your security?
A Hash is a digital fingerprint unique to each file. It is a alphanumeric string generated by a mathematical algorithm (like SHA-256). Its main feature is that it is "one-way": you can get the Hash from a file, but you cannot reconstruct the file from its Hash.Using an online hash verifier is essential when downloading software, ISO images, or sensitive documents. Authors usually publish the MD5 or SHA256 of their files so that you can verify that what you have downloaded is exactly what they uploaded, without corruption or malicious injections.# SHA-256 vs MD5: Which one should you use?
The MD5 algorithm was very popular for years due to its speed, but today it is considered cryptographically insecure as it is susceptible to "collisions". However, it is still used for simple integrity checks (corrupted downloads).If you seek maximum security, SHA-256 (part of the SHA-2 family) is the standard recommended by security agencies worldwide. It is virtually impossible for two different files to produce the same SHA-256 Hash.# Total Privacy: Calculation 100% in your browser
No Upload Needed
Our tool uses the power of your computer to process the file. By using the Web Crypto API, we don't need to "upload" the file to any server. This means you can verify files of several gigabytes in seconds, without consuming your internet bandwidth and ensuring that the content of your files never leaves your device.