SHA-256 and SHA-1 Hash Generator
Generate SHA-256, SHA-384, SHA-512 and SHA-1 hashes from any text or file. Computed in your browser with the native Web Crypto API.
Runs entirely in your browser — nothing is uploaded
The default choice for checksums and signatures.
What a hash actually is
A cryptographic hash turns any input — three characters or a four-gigabyte disk image — into a fixed-length fingerprint. The same input always produces the same fingerprint, and changing a single bit produces one that looks entirely unrelated.
That last property is the useful one. You cannot tell from two hashes whether the underlying files were nearly identical or completely different, which is exactly why comparing hashes is a reliable way to detect that something changed, however slightly.
Verifying a download
This is the everyday use. A project publishes the SHA-256 of its installer; you hash the copy you received and compare. If the two strings match, your file is byte-for-byte the one that was published.
- Switch to the File tab and choose your download.
- Select the same algorithm the site published — SHA-256 in almost all cases.
- Paste the published value into the comparison box. The check is case-insensitive and ignores surrounding whitespace.
One limitation worth being honest about: this proves the file matches what the page said, so it catches corrupted downloads and interrupted transfers reliably. It only proves authenticity if the published hash itself is trustworthy — an attacker who can alter the download page can alter the hash on it too. For that, you need a signature rather than a checksum.
Which algorithm to use
- SHA-256 — the default for essentially everything. Widely supported, no known practical weaknesses.
- SHA-512 — a wider digest, and genuinely faster than SHA-256 on 64-bit processors despite the larger output.
- SHA-384 — a truncated SHA-512, seen mostly in specific TLS cipher suites.
- SHA-1 — broken since 2017, when a practical collision was demonstrated. Included only so you can check against legacy systems that still publish it. Never choose it for anything new.
MD5 is deliberately absent. It is thoroughly broken, and the Web Crypto API built into browsers refuses to implement it at all — a decision by the standards authors that this page simply inherits.
Hashes are one-way
There is no operation that turns a hash back into its input. Services advertising hash “decryption” are searching precomputed tables of billions of common inputs and their known hashes; they find weak passwords and dictionary words, and nothing else.
The practical lesson is about what you hash. Hashing a value drawn from a small, predictable set — a phone number, a short password, an email address — protects it far less than it appears to, because the whole set can simply be hashed and compared.
Why you should not hash passwords with SHA-256
SHA functions are engineered to be fast, and modern hardware computes billions of them per second. For password storage that speed works entirely for the attacker.
Password hashing needs an algorithm that is deliberately slow and memory-hungry: bcrypt, scrypt or Argon2, each with a unique random salt per user. If you are building authentication, reach for one of those and never a bare SHA digest.
Files never leave your device
Hashing uses the Web Crypto API, running on your own machine. The file is read from disk into memory, hashed, and discarded — nothing is uploaded, and no size limit is imposed beyond the memory your browser has available. You can hash a private archive or a confidential document without it going anywhere.
Frequently asked questions
What would I use a hash for?
Most often to verify that a file arrived intact. A download page publishes the SHA-256 of the file; you hash your copy and compare the two. If a single byte differs, the two hashes look completely unrelated.
Can I get the original text back from a hash?
No. Hashing is one-way by design. Sites that appear to reverse a hash are simply looking it up in a huge precomputed table of common inputs, which is exactly why short or predictable values should never be protected by a bare hash.
Why is MD5 not offered here?
MD5 and, increasingly, SHA-1 are broken for security purposes: attackers can craft two different files sharing one hash. The Web Crypto API deliberately refuses to implement MD5. SHA-1 is included only for checking against legacy systems that still publish it.
Should I hash passwords with SHA-256?
No. SHA functions are built to be fast, which is the opposite of what password storage needs. Use a deliberately slow algorithm designed for the job, such as bcrypt, scrypt or Argon2, always with a unique salt per user.
Does hashing a large file upload it?
No. The file is read from your disk and hashed in memory on your own machine. Nothing is transmitted, so you can safely check a private archive or a multi-gigabyte disk image.