File Hash Calculator

This tool reads a file you choose from your computer directly into browser memory and computes SHA-256, SHA-384 and SHA-512 hashes for it. These digests act as a unique fingerprint: if even one bit of the file changes, the resulting hashes are completely different.

File hashing is a core part of verifying software downloads, confirming forensic evidence has not been altered, and sharing indicators of compromise. Incident responders routinely hash suspicious files before submitting them to malware analysis sandboxes or checking them against threat intelligence feeds, since hashes can be shared and compared without ever exposing the file itself.

When a file is selected, the browser's File API reads its contents into an ArrayBuffer entirely in memory. That buffer is passed to crypto.subtle.digest() for each algorithm, and the resulting bytes are converted into hexadecimal strings for display. None of this requires -- or uses -- a network connection.

1. 1Drag a file onto the drop zone, or click Choose a file to open a file picker.
2. 2Wait for the tool to read the file and compute all three hashes -- larger files take longer.
3. 3Compare the SHA-256 (or other) digest against the one published by the file's source.
4. 4Copy any digest you need to share or record for documentation.

Before installing software downloaded from a mirror, you can hash the installer and compare it against the checksum published on the vendor's official site to confirm it was not corrupted or tampered with in transit. During an incident, a responder might hash a suspicious attachment found on a compromised machine and search that hash on a threat intelligence platform to see whether it is already known.

• Comparing hashes from different algorithms (e.g. a published SHA-256 against a computed SHA-1).
• Assuming a matching hash proves a file is safe -- it only proves the bytes match a specific reference, not that the reference itself is trustworthy.
• Re-hashing after opening or editing a file, which changes its bytes and therefore its hash.
• Sharing full files instead of just hashes when trying to check a suspicious file with colleagues or online services.

Hashing a file locally is safe precisely because the file stays on your machine -- this tool never uploads it. When investigating potentially malicious files, treat the file itself with caution (avoid opening or executing it) even though hashing it is harmless. Always prefer SHA-256 or stronger over MD5 or SHA-1 when sharing hashes for security purposes, since the older algorithms have known collision weaknesses that can be exploited to forge matching files.