Are my files uploaded when calculating a SHA-256 hash?

No. Files are read locally into your browser memory via the FileReader API and digested through the native Web Crypto API. No bytes are sent across the internet.

How does file hash verification work?

Paste the publisher's expected hash into the verification field. The tool will compute the local file checksum and compare them in real time to guarantee the file has not been corrupted or tampered with.

Dev Tools · Cryptography

Hash & Checksum

Compute MD5, SHA-1, SHA-256, SHA-512, CRC32, and HMAC checksums for strings and files. 100% in-browser.

Input String

Hash Matcher & Options
UPPERCASE

Compare with expected hash (Optional)

Calculated Hashes

Understanding Cryptographic Hash Functions

A cryptographic hash is a one-way mathematical algorithm that converts an input of any size into a fixed-length string of bytes. A single-bit change in the input produces an entirely unrecognizable output (the avalanche effect).

Why is SHA-256 preferred over MD5?

MD5 and SHA-1 have known collision vulnerabilities and should only be used for non-security checksums. SHA-256 and SHA-512 remain cryptographically secure and collision-resistant for digital signatures, blockchain blocks, and certificate verification.

What is HMAC?

HMAC (Hash-based Message Authentication Code) combines a cryptographic hash function with a shared secret key, verifying both the data integrity and the authentic origin of a message (e.g. webhook signatures like Stripe or GitHub).