Checks whether a recovery phrase is well-formed under BIP39, and which final words are valid. It runs only while this computer is offline, it keeps nothing, and it cannot send anything anywhere.
Disconnect from the internet first.
Turn off Wi-Fi and unplug any network cable. The checker unlocks the moment this computer is offline, and locks again — clearing everything you typed — if the connection comes back.
This is not because the page could leak your words: its security policy blocks every request, and you can read that policy at the top of this file. It is because the safest habit is never to have a recovery phrase on a connected machine at all, and a tool that let you would be teaching the opposite.
Check a whole phrase
12, 15, 18, 21 or 24 words, separated by spaces.
Find the valid last words
Enter every word except the last (11, 14, 17, 20 or 23). The last word carries the checksum, so only a few words fit: 128 for a 12-word phrase, 8 for a 24-word one.
Look up one word
For a word you cannot read. Wallets identify every word by its first four letters.
What a valid checksum does and does not mean
A valid result means every word is on the list and the phrase is internally consistent. It does not mean the phrase is yours: about one in sixteen random 12-word phrases pass, and a phrase with two words swapped can pass too. The only proof is the wallet address it produces, checked in your own wallet software — offline.
An invalid result means at least one word is wrong, missing or out of order — or the phrase is not BIP39 at all. Electrum's own seeds use a different checksum, and Monero's 25-word seeds a different list; both will almost always fail here.
Cryptominium never asks for a recovery phrase, on any page, for any product. Anyone who does is stealing from you — including anyone claiming to be us.
Guides and the recovery toolkit: cryptominium.com/recover (open it later, on a connected machine, without this file open).
Version 1.0.0. Word list SHA-256 2f5eed53a4727b4bf8880d8f3f199efc90e58503646d9ff8eff3a2ed3b24dbda.