Seed phrase checker and fixer
Wallet says your recovery phrase is invalid? This finds which word is wrong and what it should be, using the real BIP39 checksum math, not a guess.
What this needs, and what it doesn't. This tool has to see the phrase to check it, there's no way around that. Here's what it promises instead: it never transmits anything, anywhere (zero network requests, check your browser's network tab), it never stores anything (no cookies, no localStorage, nothing written to disk), and it never asks for more than the phrase itself. No passphrase, and it never derives keys, addresses, or balances.
Given that, be deliberate about where you type a full phrase. Safest: download the offline copy, disconnect from the internet, run it, and close the browser before reconnecting. Also fine on the live page: type only the single word you're unsure about, not the whole phrase.
Nothing typed here is uploaded or saved. State lives only in this tab and disappears when you close it.
How seed phrase validation works
The 2048-word list
BIP39 is the standard most software and hardware wallets use to turn a random number into a human-writable backup. It defines a fixed list of 2048 English words; every seed phrase is built entirely from words on that list, in a specific order.
Why no two words share their first four letters
The list is deliberately designed so the first four letters of every word are unique. That means software (and a person, if they're careful) can identify the intended word from a truncated or partly-misspelled entry, and it's why this tool's suggestion ranking leans on that same four-letter prefix first.
The checksum: the last word isn't fully free
Each word encodes 11 bits of data. For a 12-word phrase, the first 11 words (121 bits) are your actual entropy, and the last word carries 7 bits of that entropy plus a 4-bit checksum computed by hashing the entropy with SHA-256. That's why not every combination of otherwise-valid words forms a valid phrase, and why a single wrong word is often catchable by math alone.
"Invalid word" versus "failed checksum"
These are two different problems. An invalid word means what you typed isn't on the BIP39 list at all, usually a typo or a word from a different list. A failed checksum means every word you entered is on the list, but the combination doesn't satisfy the checksum, meaning at least one word (even though it's spelled correctly) is the wrong word for that position.
A valid phrase can still show an empty wallet
Passing this checker only confirms the phrase is structurally valid BIP39, not that it's the right phrase for your coins, or that your wallet software will find them. Three common reasons a valid phrase shows no funds: a different derivation path than the wallet expects, a passphrase (sometimes called a 25th word) that was never entered, or a different wallet standard entirely (Electrum and some others don't use BIP39 at all). If that's your situation, read about seed phrase recovery or get in touch.
What this tool doesn't do
It validates and repairs the phrase itself, nothing more. It never derives keys, addresses, or balances, and it never asks for a passphrase. If you're evaluating whether a *service* claiming to do more than that is trustworthy, use the recovery scam checker before you send anyone anything.
Further reading
If you're deciding between backup schemes on a Trezor, see Shamir versus BIP39 backups: Shamir-split shares use a different word list entirely and won't validate here.
FAQ
Is it safe to type my seed phrase here?
Only offline. This page's script never transmits anything, anywhere, and never stores anything: no cookies, no localStorage, nothing written to disk. But typing a live phrase into any browser while you're online carries risk you don't control (malware, a compromised extension, a bad update), which is exactly why the offline copy and the GitHub source exist. Safest: use the offline copy disconnected from the internet, or type only the single word you're unsure about instead of the whole phrase.
My phrase is valid but my wallet is empty
A valid checksum doesn't mean it's the right phrase for your coins, or that your wallet is reading it the way you expect. The usual causes are a different derivation path, a passphrase (25th word) that wasn't entered, or a wallet standard other than BIP39. Read more about seed phrase recovery, or get in touch and I'll help you narrow it down.
I'm missing 2 or more words
This tool won't enumerate for you past 1 missing word, because the number of checksum-valid combinations gets too large to browse (roughly 260,000 for 2 missing words in a 12-word phrase). That volume of blockchain checking is exactly the GPU work I do professionally. Missing 2 or 3 words is often still recoverable: a free assessment costs nothing, and there's no fee unless your coins come back.
Does this work for Ethereum or other coins?
Yes. BIP39 is shared across almost every chain built on it (Bitcoin, Ethereum, and most others), so validating the phrase and checksum is coin-agnostic. What differs by coin and wallet is the derivation path used to turn that phrase into addresses, which this tool deliberately doesn't touch.
What about 25th-word passphrases?
Not checkable, by design. A BIP39 passphrase is any string you choose; there's no checksum on it, so any passphrase you type is "valid" whether or not it's the one you actually used. This tool never asks for one.