BIP39 Mnemonic Generator

BIP39 Mnemonic Generator. Generate a BIP39 mnemonic phrase from random entropy or convert an existing mnemonic back to entropy — free online seed phrase generator with multi-language support.

Create secure BIP39 mnemonic phrases instantly with our free mnemonic generator.

Enter or generate random entropy to produce a standard 12, 15, 18, 21 or 24-word seed phrase (128 to 256 bits of entropy), or paste an existing mnemonic to recover its underlying entropy.

Supports 10 BIP39 word list languages including English, Chinese, French, Spanish, Japanese, and more — giving you full flexibility for multi-language wallet recovery phrases. Our BIP39 seed phrase generator runs entirely in your browser.

No entropy or mnemonic data is ever sent to a server, so your crypto wallet recovery phrase stays completely private.

Entropy is generated with crypto.getRandomValues, the cryptographically secure random source of your browser, and all conversions happen offline.

Ideal for developers testing HD wallet derivation, crypto users creating new wallets, or anyone needing to understand the BIP39 standard.

Frequently asked questions

How do I generate a BIP39 mnemonic phrase?

The page creates 128 bits of random entropy (32 hex characters) when it opens and shows the matching 12-word phrase in Mnemonic phrase. Pick 15, 18, 21 or 24 words under Words for a longer phrase, click the refresh button next to Entropy (hex) for a new one, choose a Language, and use the copy buttons to copy the entropy or the phrase.

Can I convert a mnemonic back to entropy?

Yes. Type or paste the words into Mnemonic phrase with the matching Language selected. If the words and checksum are valid, Entropy (hex) shows the original entropy; otherwise Invalid mnemonic phrase is displayed.

Which entropy lengths and word counts are supported?

All standard BIP39 lengths: 12, 15, 18, 21 or 24 words, from 128, 160, 192, 224 or 256 bits of entropy, which is 32, 40, 48, 56 or 64 hex characters. Typing entropy of one of these lengths selects the matching word count, and any other length is rejected.

Which BIP39 word list languages are available?

English, Chinese simplified, Chinese traditional, Czech, French, Italian, Japanese, Korean, Portuguese and Spanish, the official BIP39 word lists. The same entropy gives a different phrase in each language, so note which list you used.

Is it safe to create a real wallet seed phrase here?

Entropy is generated in your browser with a cryptographically secure random source, and nothing is sent to a server. Still, any seed phrase shown on an internet-connected computer can be exposed to malware or screen capture, so for wallets holding real funds let your hardware wallet or wallet app generate the phrase.

How to use this online tool

BIP39 Mnemonic Generator is designed for fast browser workflows when you need to format, validate, convert, decode, encode, generate, or inspect data without opening a heavy desktop app. Start with the input field or visible options, review the result, then copy or download the output for the next step.

Private processing in your browser

BIP39 Mnemonic Generator keeps the normal processing step local in your browser. That is useful for code snippets, tokens, documents, configuration values, text samples, and other material that should not be sent to a remote service unless you explicitly choose to share it.

When this tool is useful

Use BIP39 Mnemonic Generator for repeatable developer tasks, technical documentation, QA checks, quick conversions, debugging, content cleanup, and internal team workflows. The page focuses on clear inputs, immediate feedback, and output that is easy to reuse in code, reports, tickets, emails, or notes.

Practical tips

Before copying the final result, check important details such as spacing, casing, filenames, encoding, token structure, line breaks, or output format. Small checks prevent mistakes when the result is reused in source code, API requests, documentation, spreadsheets, or shared files.