File Hash Checker

Calculate and Compare the File Hash

This file hash checker calculates a local file’s SHA-256 digest and compares it with an optional recorded digest. The file stays on your device.

Choose a file, then paste the expected digest from your handover record. A SHA-256 digest has 64 hexadecimal characters, using 0–9 and a–f. Uppercase letters and surrounding whitespace are accepted.

Calculated means you have a digest but have supplied no reference. Match means the digests agree. Mismatch means they differ. An invalid reference must be corrected before comparison or export.

The tool uses the browser’s Web Cryptography digest operation. It reads the complete file into memory and accepts up to 100 MiB. Browser memory or file-access failures can still prevent processing.

Keep the Integrity Record With the Source

Preserve the received original before making an edited working copy. Save the integrity record beside the handover record, including how you received the file and who supplied the reference.

The downloadable record contains the filename, exact size in bytes, SHA-256 algorithm and computed digest. It also records the entered reference and comparison result. Copy or download it before closing this tab.

The synthetic example hashes a three-byte text file containing abc, with no newline. Its digest is ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad, matching NIST’s SHA-256 example.

Two synthetic files containing those same three bytes have the same digest, even if one is renamed. A changed copy containing abd produces a different digest. Adding a newline also changes the bytes. The filename is recorded for identification and plays no part in hashing.

File properties can help describe a received document. Read document metadata evidence for the limits of those observations.

Understand What a Match Establishes

A match with a trusted, independently recorded reference supports the conclusion that the file’s bytes are unchanged. SHA-256 is designed to make different files with the same digest computationally infeasible to find.

The reference’s origin matters. Calculating a new digest from an already altered file cannot establish what an earlier version contained. Keep the reference through a trusted channel or record that an altered file cannot silently replace.

Hashing establishes neither authorship nor the truth of a document’s contents. It cannot establish that acquisition was lawful. A hash check also performs no malware scan, metadata interpretation or digital-signature verification.

A complete chain-of-custody procedure records acquisition and subsequent handling alongside integrity checks. For the underlying records’ provenance and use in proceedings, read bank statements as evidence.