Input
Preparing your workspace…
How to use
- Choose or drop a local file and select an algorithm.
- Select Generate; watch progress or cancel if needed.
- Compare a trusted expected digest, copy a checksum or download JSON.
File Checksum
File checksums help compare the bytes of a downloaded file with an expected digest. The file is read locally in chunks, so it does not need to be uploaded or decoded as text.
Compare a calculated digest with the full expected checksum rather than a prefix. Progress and cancellation remain available while a large file is being read.
Work with the input
Choose or drop a local file, select SHA-256 or another algorithm, then select Generate.
Watch progress or cancel a long calculation. The original filename and byte size remain visible.
Empty file · SHA-256e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855Example data only. Never reuse sample secrets as real credentials.
Behavior and limits
Files up to 1 GiB are processed in 1 MiB chunks, with a 120-second time limit. Empty files are valid. A filename is only a label and is not part of the digest. MD5 and SHA-1 are legacy options; checksum comparison does not independently authenticate a publisher.
Copy and reuse
Paste the expected digest from a trusted source. Compare, copy or download the calculated checksums.
Copy all digests · Comparison uses the selected output format. With All algorithms, any matching digest is identified.
Input: 1 MiB; Secret key: 64 KiB; File: 1 GiB; Passwords: 4–128 (Length), 1–100 (Count); bcrypt: 1–72 UTF-8 bytes · cost 4–14 · default 10; AES: Plaintext 1 MiB, Passphrase 1 KiB, GCM / CBC / CTR / CFB / ECB, 128/192/256-bit; PBKDF2 / HKDF: Password / input bytes 64 KiB, Salt / info 1 KiB, Output length (bytes) 1–256; 1–256 output bytes · up to 2,000,000 PBKDF2 iterations · inputs stay on your device; Time: 30 s; File: 120 s.
Frequently asked questions
Is my file uploaded?
No. A local browser Worker reads the chosen file. Selecting it does not give the tool access to unrelated files.
Does a matching checksum prove a download is safe?
No. It shows a match with the supplied digest under the chosen algorithm. You still need to trust the digest source and choose an appropriate integrity-checking algorithm.
Does a large file have to be read into memory all at once?
No. The Worker reads it in chunks and reports progress. The file-size limit still applies, and Cancel stops the current calculation.
What is included in the JSON report?
The report includes the filename, byte count, output format and calculated digests. It does not contain the original file bytes.
Does renaming a file change its checksum?
No. Only file contents are hashed; the filename and modification time are not part of the digest input.