Compare two file checksums

Supply the checksum recorded at the source and the checksum calculated at the destination with the same algorithm. This tool compares them without treating uppercase and lowercase letters as different, rejects values of unequal length, and returns an unambiguous match result. It does not upload, inspect, or hash the file itself, so you retain control of both the file and the checksum calculation process.

Compare the source and destination values

Calculate a checksum for the file before it leaves its source, then calculate another checksum after the transfer finishes. Both calculations must use the same algorithm and settings. Paste the first value into checksum_before and the second into checksum_after. The comparator removes surrounding whitespace, confirms that neither value is empty, and checks that both values contain the same number of characters. It then compares the strings without distinguishing uppercase from lowercase. This behavior is useful for hexadecimal digests because one utility may print lowercase letters while another prints uppercase letters even though the underlying bytes are identical. A true match means the supplied checksum representations agree; a false match means at least one character differs. The result also reports the validated length, which helps document the representation that was compared. The tool deliberately does not infer an algorithm from that length, because multiple checksum formats can share a length and an algorithm name cannot be proven from a string alone. Record the algorithm separately in your transfer procedure so that the destination calculation reliably matches the source calculation method.

Interpret a match without overstating it

When the result is true, the two checksum strings are equal after case normalization. That is strong evidence that the transferred file produced the same digest as the source file under the selected algorithm. It is not evidence that this page calculated either checksum, because the comparator receives only the two strings. It also cannot detect an incorrect operational step in which both values were copied from the same place or calculated from the wrong file. When the result is false, repeat both checksum calculations directly against the intended files before retransferring anything. A mismatch can indicate corruption, an incomplete upload, text-mode conversion, a changed archive, or simply a pasted value from another artifact. Different lengths produce an error rather than false because the capability assumes both values came from the same algorithm. Under that assumption, unequal representations signal a setup or copy error that should be corrected before equality has any useful meaning. Case is the only representational difference ignored. Internal spaces, punctuation, prefixes, or separators remain part of the supplied value, so use comparable output formats or remove tool-specific decoration before submitting the checksums.

Build checksum comparison into a transfer workflow

For an occasional download, calculate the source and destination checksums with trusted local tools, keep the algorithm visible in your notes, and use this comparison for a clear second check. For automated delivery, store the source checksum beside the artifact or in a signed manifest, calculate the destination value after the final write completes, and call the API before marking the transfer successful. A mismatch should stop publication or deployment and preserve enough context to investigate, while a malformed or unequal-length pair should be treated as a configuration error. Choose the checksum algorithm according to the threat and reliability model of the workflow. Modern cryptographic hashes are appropriate when accidental corruption and deliberate substitution matter; older or shorter checksums may still be useful in constrained systems but provide different assurances. This capability does not recommend or enforce an algorithm because its job is intentionally narrower: compare two values that your workflow already produced using the same method. The deterministic solver uses no network, model, random value, or clock. The browser and API therefore return the same result for the same inputs, and automated systems can perform the comparison for $0.002 per request without sending the underlying file.