Private SHA-256 file checksum
Calculate a file’s SHA-256 checksum locally and compare it with an expected value from a trusted source.
The 64-character SHA-256 checksum will appear below.
The browser reads the whole file into memory and hashes it locally. No file upload occurs. A matching checksum is not a malware scan or proof that a file is safe.
A fingerprint of bytes, not a safety certificate.
SHA-256 deterministically turns file bytes into a 256-bit digest, commonly displayed as 64 hexadecimal characters. This tool uses the browser’s Web Crypto digest implementation. The filename is not part of that calculation; changing the bytes, including a text file’s line endings, generally changes the checksum.
The exact three bytes abc, without a trailing newline, have this SHA-256 checksum:
61a396177a9cb410ff61f20015ad
The sample button runs that known input through the same hashing operation used for a selected file. It does not read a file from your device.
The expected hash needs a trustworthy source.
A match means the digest equals the expected value. It does not establish who created a file, whether it is free of malware or whether the expected value itself is genuine. If an attacker changes both a download and the hash posted next to it, comparing those two alone will not authenticate the publisher. Use the publisher’s official verification guidance, including signed checksums where provided.
Web Crypto’s digest API reads the entire input into memory. This page limits files to 100 MiB, and a low-memory device may still struggle. Use tools such as sha256sum on Linux or Get-FileHash -Algorithm SHA256 in PowerShell for large files. A browser error does not mean the file is corrupt.
Follow the complete checksum-verification guide · Web Crypto digest documentation ↗.
A few useful answers
Does a matching checksum mean the file is safe?
No. It means the digest matches the expected digest. Authentication of the expected value and checking the file’s safety are separate tasks.
Why does a copied text file produce a different hash?
Line endings, encoding, a byte-order mark or a trailing newline can change the bytes even when displayed text looks the same.
Is SHA-256 encryption?
No. A checksum is a one-way digest. This tool does not encrypt, decrypt or recover file contents.