Is it safe to paste my real seed phrase here?

It's as safe as any locally-running web app — the seed never leaves your browser (no network calls). But for max safety, test with a sample or dummy mnemonic, or run this offline. Never type your seed into a computer you don't fully trust.

What is the BIP39 checksum?

The last word of a BIP39 mnemonic isn't random — its first few bits encode a SHA-256 checksum of the entropy. This lets wallets detect a single mistyped word. We verify this checksum locally.

Why are 12/15/18/21/24 words the only valid lengths?

BIP39 supports 128/160/192/224/256 bits of entropy, which translate to those exact word counts (each word encodes 11 bits, plus 1 checksum bit per 32 entropy bits). Other counts are invalid by spec.

Which wordlist is used?

The official English BIP39 wordlist (2048 words). All four BIP39 wordlists (English, Japanese, Korean, Spanish) are spec-defined — most wallets use English. We support English only; mixed-language mnemonics are invalid.

Can this tool recover a forgotten word?

Not automatically. If exactly one word is wrong and you know its position, you could brute-force the 2048 possibilities — that's a feature we may add. For now, you'll see exactly which words are unrecognized.

Does this tool generate new seed phrases?

No, by design. Generating a high-quality seed phrase requires cryptographic randomness and an air-gapped environment — use a hardware wallet or an offline tool like Ian Coleman's BIP39 tool.

BIP39 Seed Phrase Validator

Check recovery phrases word-by-word against the BIP39 wordlist and verify the checksum.

100% private — no uploads Free & unlimited Read tutorial

See how it works

Watch a quick simulation of this tool in action — no file needed.

How to use BIP39 Seed Phrase Validator

Follow these steps — everything happens instantly in your browser.

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Step 1. Type or paste your seed phrase into the secure input (12, 15, 18, 21, or 24 words).
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Step 2. Each word is validated against the official BIP39 wordlist as you type.
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Step 3. The checksum (last word's checksum bits) is verified once the word count is valid.
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Step 4. Read the result — green means a valid mnemonic, red means an invalid word or failed checksum.