Security Notes

A seed phrase is the master backup of a wallet: whoever has the words controls the funds. This page explains how the tools on bip39-phrase.com handle the data you give them, what the site itself collects, and the habits that keep a phrase safe.

How the tools work

The six BIP39 tools — the seed phrase generator, the seed phrase to private key converter, the private key generator, the checksum checker, the last word calculator and the BIP39 visualizer — run entirely in your browser. Randomness comes from the browser's crypto.getRandomValues(), and the cryptography from the audited open-source libraries @scure/bip39, @scure/bip32 and @noble/curves.

The site is static: there is no backend, no account and no database, and these tools make no network requests with what you enter or generate. Once a tool page has loaded, it keeps working with the network switched off, which you can check yourself. The one exception on the site is the off-topic IPv6 WHOIS lookup, which by design sends the address you enter to public registry (RDAP) servers.

What the site collects

Pages load analytics services (Google Analytics 4, Yandex Metrica and Microsoft Clarity) that receive usage data such as the pages you visit, clicks and scrolling, your browser and device, and an approximate location; the hosting server and Cloudflare, which delivers the site, see your IP address in their logs. The privacy policy lists what each service receives and how to opt out.

Keep the phrase offline

• Write the phrase on paper or stamp it in metal. Never keep it in screenshots, photos, cloud notes, password-manager notes you sync, email or chat apps: anything online can leak. Our guide on how to store a seed phrase compares paper, metal and split backups.
• Keep at least two copies in separate places, so one fire, flood or burglary doesn't take both. A metal backup survives heat and water that destroy paper.
• Check a new backup before it holds real funds: restore it in the wallet and compare the first receiving address. The restore guide covers the common wallets.
• For long-term storage, 24 words (256 bits of entropy) give extra margin; 12 words (128 bits) already put brute force out of reach. See 12 vs 24 words.
• An optional BIP39 passphrase turns the same words into a different wallet. It protects against someone who finds the words, but if you lose the passphrase, the funds are gone too — back it up separately.
• Never make up the words yourself: people pick predictable words, and a phrase that is not random can be guessed. Why, in numbers: why you should never create your own seed phrase.
• Plan for your heirs without handing anyone the phrase today: crypto inheritance covers letters of instruction, multisig and split backups.

Recognise the scams

• Nobody legitimate asks for your phrase. Wallet support, exchanges, "recovery services" and "validators" never need the words; anyone who asks for them is trying to steal the funds.
• Fake wallet apps and sites. Install wallets only from the maker's own site or the official store listing it links to, and check the domain before you type anything. Read how to protect a wallet from phishing.
• "Leaked" phrases with a balance. A phrase posted in a chat or comment with tokens on it is bait: the coins you send for fees are swept at once. The seed phrase scams guide walks through this and other tricks.
• Signs of a compromised phrase — and what to do first — are in is my seed phrase compromised?

About the PDF archives and example phrases

The seed phrase PDF archive and the private key PDF archive are reference documents. Every phrase, key and address printed in them, in articles or on tool pages, including the official BIP39 test vectors, is public by definition: anyone can read it, so it must never hold funds.

Report a security problem

If you find a flaw in a tool — a wrong derivation, a weak random source, a page that loads something it shouldn't — write to info@bip39-phrase.com with the page address and how to reproduce it. Don't post exploitable details publicly before we have answered. Mistakes in articles can be reported the same way; see about the site.

Not financial advice

Content on bip39-phrase.com is educational information about cryptography standards and wallet technology. It is not investment, legal or financial advice, and the tools are not a wallet. The terms of use apply.