Calculate a file's SHA-256 checksum locally, then compare it with a reference you independently trust.
Your file is read in bounded pieces in this browser. This tool does not intentionally transmit the file, filename or checksum, and does not save a history. Nothing is calculated until you choose Calculate SHA-256.
A matching checksum shows agreement with the supplied value. It does not prove publisher authenticity, malware safety or a valid digital signature.
Select a file
Any file type, including binary, extensionless and zero-byte files. Maximum 16 GiB. No content is decoded or rendered, and your original file is unchanged. Files above the limit are rejected without a partial checksum.
Calculate SHA-256
Reads one slice at a time, at most 1 MiB, and yields between bounded hash updates. Processing speed varies. Cancel stops new work; a pending native slice read may still need to finish before retry.
The percentage describes bytes processed. Even at 100%, the checksum is available only after SHA-256 finalisation succeeds.
Compare with a trusted reference (optional)
Paste exactly 64 hexadecimal characters. Surrounding whitespace and uppercase/lowercase are accepted. Paste the checksum alone, without a filename or labels. You can edit this before or after calculation; changes do not reread the file.
Not compared
Obtain the expected value through a source you independently trust. Agreement with an untrusted checksum does not establish that a file is safe or authentic.
Calculated SHA-256
Checksum line and file
The simple checksum line contains the full digest, two spaces and the unchanged source basename. Ordinary spaces and Unicode work. Ambiguous names needing escaping have no line export; the raw digest remains usable. The fixed download checksum.sha256 contains one UTF-8 line ending in a newline. It does not contain the original file.
Reset or leaving the page clears this page's file reference, results and download URLs. Previously initiated clipboard writes cannot be recalled. This does not promise secure erasure from browser/OS memory or isolation from compromised extensions or scripts.