Y YSeed
BIP39 English / browser-only / no server custody

Free secure seed phrase generator

A calm, trust-first utility for generating BIP39 phrases locally with Web Crypto. No account, no phrase API, no server custody.

Trust contract Generate, verify, write down, wipe. Nothing leaves this device.
Runtime
Static app
Phrase state
JS memory
Saved data
Theme only
No accounts No phrase API No phrase storage Offline-ready

Generation chamber

Create the phrase locally.

Web Crypto Memory only
Ready for a private screen. Generate after you close screen sharing and cloud notes.

Clipboard can sync across devices. Copy only for tests or offline use.

24 words

256 bits of entropy plus 8 checksum bits.

Entropy 256 bits
Checksum 8 bits
Wordlist English 2048

Safety controls

Default-deny by design.

locked
  1. 01Private screen
  2. 02Generate offline
  3. 03Write on paper
  4. 04Wipe screen

Live privacy receipt

What the page is allowed to know.

no telemetry
Random source Checking Web Crypto
Connection local first
Requests after load 0 captured
Phrase storage Memory only
01

No seed phrase backend.

YSeed is a static client-side tool. V1 has no account system, database, wallet lookup, or endpoint that receives a phrase.

  • Generation happens in the browser.
  • Validation checks words and checksum locally.
  • No address lookup or wallet balance check.
02

No persistence.

Generated seed phrases are not written to localStorage, sessionStorage, cookies, or the URL. Only the visual theme preference is saved.

03

Offline ceremony.

Load once, disconnect, generate, write down, validate if needed, then wipe the screen. Treat clipboard as unsafe unless you are testing.

BIP39 Validator

Check word count, English wordlist membership, and checksum. Do not paste a real wallet recovery phrase into any live website.

Paste or type a phrase to inspect it.

Use demo or test phrases only in the live website. Real wallet recovery phrases belong offline.

No server checks No address lookup

What is YSeed?

YSeed is a free, client-side BIP39 seed phrase generator for education, test wallets, and offline generation workflows. It creates phrases entirely in your browser using the Web Crypto API.

The trust-first rule is simple: the app should help you generate and understand a phrase without becoming a new place where that phrase can leak.

How YSeed generates BIP39 phrases

  1. Select 12, 15, 18, 21, or 24 words.
  2. Generate entropy locally with crypto.getRandomValues().
  3. Add BIP39 checksum bits and map 11-bit chunks to the English wordlist.
  4. Write the phrase offline and wipe it from the interface.

BIP39 English wordlist

Search the same 2048-word list used by the generator and validator.

Showing words