Question 1

What is a file hash or checksum?

Accepted Answer

A file hash (or checksum) is a fixed-length string produced by running a file through a cryptographic hash function. Even a tiny change to the file produces a completely different hash. This makes hashes useful for verifying file integrity and detecting tampering.

Question 2

Which hash algorithm should I use?

Accepted Answer

For security-sensitive purposes, use SHA-256 or SHA-512 — they are the current standard. SHA-1 is deprecated for security use but still used for non-security checksums (e.g., Git commit hashes). SHA-384 is a truncated version of SHA-512.

Question 3

Does this tool upload my file anywhere?

Accepted Answer

No. This tool uses the Web Crypto API (SubtleCrypto.digest()) which runs entirely in your browser. The file is read into memory locally and hashed on your device. Nothing is sent to any server.

Question 4

How do I verify a downloaded file?

Accepted Answer

Download the file, then drag it into this tool. The download page will usually list an expected SHA-256 hash. Copy that hash and paste it into the 'Expected Hash' field — the tool will tell you if it matches.

Question 5

Why is MD5 not available?

Accepted Answer

MD5 is not supported by the browser's native Web Crypto API (SubtleCrypto) because it is considered cryptographically broken. For file integrity checks, SHA-256 is the widely accepted replacement.

File Hash Checker

File Hash Checker