Hash Generator & Checker
Create a modern SHA-2 checksum from pasted text or one selected file without uploading it. Choose SHA-256, SHA-384, or SHA-512, copy or download the generated hexadecimal digest, and compare it with a publisher-provided checksum using format-aware match and mismatch feedback.
What a Hash Does
A cryptographic hash turns an input of any practical length into a fixed-length digest. The same bytes and the same algorithm produce the same digest every time, while a small input change produces a different result.
This tool generates SHA-256, SHA-384, and SHA-512 digests in your browser. The displayed value is hexadecimal text, which is the format software publishers commonly list alongside downloads.
How to Verify a Download
Choose the same algorithm that the publisher used, select the downloaded file, and generate its hash. Paste the publisher-provided checksum into the verification field. A match means the two digest strings are identical after harmless whitespace and letter-case normalization.
Get the expected checksum from a channel you trust. A matching checksum alone does not prove who published the value; a signed release or signed checksum can provide an additional authenticity signal.
Why This Tool Uses SHA-2
SHA-256, SHA-384, and SHA-512 are members of NIST's Secure Hash Standard and are supported by the browser Web Crypto API. SHA-256 is the practical default when a publisher has not specified another SHA-2 algorithm.
This tool intentionally does not offer MD5 or SHA-1. Legacy hashes can still appear in old documentation, but they are poor choices for a new integrity workflow because collision attacks are known for those algorithms.
Local Processing and File Limits
Text encoding, file reading, digest calculation, comparison, copying, and checksum download happen locally in the browser. OliveZ does not receive the selected file or hash.
The browser's native digest method processes a complete memory buffer rather than a stream. This tool therefore accepts one file up to 100 MB and explains the limit before processing starts.
A Match Is Not a Safety Verdict
A match says only that the selected input and expected checksum produce the same digest under the selected algorithm. It does not scan the file, establish that the checksum came from a trusted publisher, or verify a digital signature.
If the publisher supplies a signed checksum, verify the signature with the publisher's documented method. Never treat a mismatch as proof of malware; it can result from a different version, incomplete download, wrong algorithm, or copied checksum error.
Examples
Verify a software installer
Input
A publisher lists a SHA-256 checksum next to an installer download.
Show result
Result
Select the installer, generate SHA-256, paste the published value, and review Match or Mismatch.
Use the publisher's official release page or signed checksum file as the expected-value source.
Hash an exact text value
Input
Paste a configuration snippet and choose SHA-512.
Show result
Result
A SHA-512 hexadecimal digest that can be copied or downloaded locally.
Text is hashed as UTF-8, so whitespace and line endings are part of the input.
Find a copied checksum error
Input
Paste a SHA-384 checksum with one changed character.
Show result
Result
Mismatch, because every character in a digest must agree after whitespace and letter-case normalization.
Recheck the file version, selected algorithm, and expected value before downloading again.
Frequently Asked Questions
Are my file or text uploaded?
No. The browser reads, hashes, compares, copies, and downloads the data locally. OliveZ does not receive the selected content.
Which algorithm should I choose?
Choose the algorithm named by the publisher. SHA-256 is the common default for published checksums, but SHA-384 and SHA-512 require their own exact expected digest lengths.
Why is the file size limited?
The native browser digest API requires a complete input buffer rather than processing a file as a stream. The 100 MB cap helps keep memory use predictable.
Does a matching checksum prove a file is safe?
No. It shows that the selected file matches the supplied checksum. It does not perform a malware scan, verify a digital signature, or prove that the expected value came from a trusted source.
Why are MD5 and SHA-1 unavailable?
This tool focuses on modern SHA-2 integrity workflows. MD5 and SHA-1 have known collision weaknesses and are not appropriate defaults for new security-sensitive use.
Does whitespace change a text hash?
Yes. Text is encoded exactly as entered in UTF-8, so spaces, tabs, punctuation, and line endings affect the generated digest.
References
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