SHA256 Hash Generator
Calculate a standard SHA-256 digest for text or files locally and copy the exact 256-bit result as Hex or Base64.
Privacy: your files never leave your device. All processing happens locally in your browser.
How to use
- 1.Select UTF-8 text or file bytes and enter the exact content to verify.
- 2.Generate SHA-256 and copy either the 64-character Hex value or standard Base64.
- 3.Compare the complete digest with an authenticated reference and confirm both sides used the same bytes.
About SHA256 Hash Generator
SHA-256 Hash Generator produces the standard 256-bit digest for UTF-8 text or a local file. The output appears as 64 lowercase hexadecimal characters and as standard padded Base64, two representations of the same 32 bytes. All calculation takes place in the current browser tab, and the application does not upload the selected content.
SHA-256 belongs to the SHA-2 family specified by NIST FIPS 180-4. It pads a message, splits it into 512-bit blocks, expands each block into a 64-word schedule and updates eight 32-bit working values. The final eight words form the 256-bit digest. This page delegates that exact operation to the platform cryptography implementation.
Text is not hashed as abstract characters. Text mode first encodes the string as UTF-8, so the displayed byte count is part of the result context. Accented letters, emoji and scripts outside ASCII can use multiple bytes. File mode bypasses text decoding and hashes every selected byte, including headers, embedded metadata and line-ending bytes.
Use SHA-256 checksums to compare a local download with a digest published by a trusted vendor, to identify whether two byte-for-byte artifacts match, or to generate a value required by a build and deployment workflow. Copy the representation the other system expects; changing Hex letter case changes presentation, not the underlying digest bytes.
A matching digest is meaningful only when the expected value itself is authentic. If an attacker can replace both a file and the checksum displayed beside it, recomputing SHA-256 will confirm the attacker's pair. Obtain reference hashes over HTTPS from the owner, through a signed release, or through another authenticated channel appropriate to the risk.
SHA-256 is a one-way hash, not encryption. There is no key and no supported reverse operation. It also does not authenticate who created an input. Use HMAC-SHA-256 when two systems share a secret and need message authentication, or a digital signature when a verifier must establish origin using a public key.
Do not store passwords by applying SHA-256 directly. Its speed is valuable for integrity checks but also helps attackers test password guesses. Account systems should use a unique salt and a purpose-built password hashing function with calibrated memory and time cost. This page intentionally performs only the raw standard digest.
The tool accepts empty text because the empty byte string has a legitimate standard digest. Spaces, Unicode normalization forms, carriage returns and final newlines are also bytes and can change the result. When comparing with a command-line utility, make sure a shell command did not append a newline and that both sides read the same file.
Files are capped at 100 MB because the Web Cryptography digest interface used here receives the full byte buffer rather than a stream. The asynchronous job identity prevents an older file read or hash from replacing a newer selection. For much larger files, use a trusted streaming tool on the local machine instead of exhausting browser memory.
Eight golden fixtures include NIST and RFC examples plus independently cross-checked text, punctuation, UTF-8 and binary cases. The suite asserts the exact digest, its fixed 32-byte size and the standard Base64 encoding. The tests distinguish algorithm correctness from a self-consistent round trip, since hashes have no inverse.
To use the generator, select text or file input, preserve the exact bytes, generate the value and copy Hex or Base64. Compare the complete output rather than a prefix. Record the algorithm name alongside any stored digest so a 64-character SHA-256 value cannot later be confused with another format or undocumented checksum.
Methodology & sources
Exact UTF-8 text or file bytes are limited to 100 MB and passed to the browser SHA-256 digest operation from FIPS 180-4. The 32 result bytes are rendered as lowercase Hex and padded Base64.
Frequently asked questions
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