SHA1 Decrypt
Reverse a SHA-1 hash by brute force — try every short combination of characters, entirely in your browser, to recover the original text.
Input
~1.7 million combinations — may take a while.
Split the search across browser threads to check more combinations per second.
Result
Paste a hash and press Start search. The search runs entirely in your browser.
Guides
Paste a SHA-1 hash and this tool tries to recover the original text by brute force — testing every short combination of characters until one produces a matching hash. It runs entirely in your browser: the search happens on your own machine, and nothing is uploaded.
Can you actually "decrypt" a SHA-1 hash?
No — and it's worth being clear about why. A hash is not encryption. Encryption is reversible with a key; hashing is a one-way function designed so the original can't be recovered from the output. There is no "decrypt" operation and no key.
What this tool does instead is guess. It hashes candidate strings one after another and checks whether any of them matches your hash. If the original was short and simple, a guess will find it quickly. If it wasn't, no tool — this one included — can reverse it.
Isn't SHA-1 "broken"? Doesn't that make it easy to reverse?
Not in the way people expect. SHA-1 is broken for collisions — since the 2017 SHAttered research it's practical to construct two different inputs that hash to the same value, which is why SHA-1 is no longer acceptable for certificates or signatures. That's a different attack from what you want here.
Recovering the original input from a digest is a preimage attack, and SHA-1 has no practical preimage break. So the only route back is guessing, exactly as with SHA-256. A weak SHA-1 hash is weak because the input was short, not because the algorithm is dated.
Then when will it find something?
When the original input was short and drawn from a small set of characters. The number of combinations is the alphabet size raised to the length, so it grows explosively:
- lowercase, up to 4 characters → about 475,000 tries — instant.
- lowercase + digits, up to 5 → about 60 million — a few seconds to a minute.
- add uppercase and symbols, or go past 6 characters → billions or trillions — not feasible in a browser.
SHA-1 is computed a little faster than SHA-256, so the search runs slightly quicker — but "slightly quicker" against an exponential curve changes nothing about where the wall is. The tool shows an estimate of the search size as you change the settings, so you know before you start whether it can finish.
How do I use it?
- Paste the SHA-1 hash (40 hex characters).
- Tick the character sets the original might contain.
- Set the maximum length to try and a time limit.
- Press Start search. Progress is shown live, and you can stop at any time.
You can also raise the number of parallel workers to use more of your CPU cores — the search is split across them.
Is this legal / what should I use it for?
Reversing hashes of data you own or are authorised to test — recovering your own forgotten value, checking whether a password you chose is weak enough to be cracked, or CTF and learning exercises. Don't use it against data you have no right to.
Is my hash private?
Yes. Everything runs client-side in a background thread in your browser. The hash you paste and any recovered text never leave your device — there is no server involved, unlike most online "SHA1 decrypter" tools, which post your hash to a rainbow-table lookup service.
What if my hash isn't SHA-1, or I need to generate one?
A SHA-1 digest is always 40 hex characters; 32 means MD5, 64 means SHA-256, 128 means SHA-512. For those, use MD5 Decrypt (which offers all four algorithms), SHA256 Decrypt or SHA512 Decrypt. To generate a hash instead of reversing one, use the SHA Hash Generator.