File Checksum Calculator

Compute MD5 and SHA-256 checksums for any file to verify integrity — all processed locally.

File Hash Calculator

Drag & Drop File or Click to Browse

Any file type, computed locally

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What is the File Checksum Calculator?

File checksum verification is essential for confirming that downloaded files are identical to the original. Software publishers list checksums (usually SHA-256) alongside download links. After downloading, you compute the file's checksum locally and compare it character-by-character against the listed value. A match confirms the file is intact and untampered. This tool reads file bytes using the FileReader API and computes hashes via the Web Crypto API — all locally in your browser with zero network activity.

How to use the File Checksum Calculator?

  1. Drag and drop a file onto the upload area, or click to browse.
  2. The tool reads the file locally and computes MD5 and SHA-256 checksums simultaneously.
  3. Compare the displayed checksums against the publisher's listed values to verify integrity.
  4. Click 'Copy' next to either hash to copy it to your clipboard.
  5. Your file is never uploaded — all computation happens in your browser using Web Crypto APIs.

Frequently Asked Questions

How do file checksums verify integrity?

A checksum is a unique fingerprint of a file's contents. If even a single bit changes, the checksum changes completely. By comparing your file's checksum against the publisher's listed value, you can confirm the file hasn't been corrupted during download or tampered with.

Which checksum algorithm should I use?

SHA-256 is recommended for security-sensitive verification. MD5 is faster but vulnerable to intentional collision attacks — use it only for checking accidental corruption, not for verifying against malicious tampering.

Is my file uploaded to a server?

No. The file is read entirely in your browser using the FileReader API. The Web Crypto API computes the hash locally. Nothing leaves your device.

Can I check large files?

Yes, files of any reasonable size can be hashed. The browser reads the entire file into memory, so very large files (500MB+) may take a moment depending on your system's RAM.