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Seed safety tools

Four small tools for people who keep their own bitcoin seed. Each one answers a common question with plain numbers and links every fact to its official source. None of them asks for anything secret.

Last reviewed:

The tools

  • Something went wrong

    Was my seed affected by the 2026 Coldcard flaw?

    For: Anyone who made a seed on a Coldcard.

    Up to six questions: the model, where the words came from, the firmware, any dice you added and how the funds are protected. You see whether the July 2026 entropy flaw affects it and what to do, without typing anything secret.

  • Check what you have

    Seed backup checkup

    For: Anyone who keeps their own seed backup, on paper or metal.

    Eight short questions (yes, no or not sure) about how your backup was made, tested and stored, with a to-do list you can print. It never asks for a single word.

  • Making a new seed

    How many dice rolls do I need?

    For: Anyone about to create a new seed with dice.

    Shows how much randomness your rolls give (50 for 12 words, 99 for 24), how to roll properly, and how each device uses dice in its own way.

  • Sharing a backup

    Why you should never cut your seed into pieces

    For: Anyone thinking of splitting their seed between places or people.

    Shows how much one piece gives away (one card of a three-card split leaves about 80 bits to guess, not 256) and the standard ways to share a backup safely.

How these tools work

  • They never ask for secrets. They count rolls and words, or ask yes-or-no questions about your device and your habits.
  • Nothing you enter or choose in them is sent or saved. Any math runs in your browser and is gone when you close the page.
  • They work without JavaScript. Every answer is also printed as plain text and tables, so the pages read fine with scripts turned off, for example in Tor Browser's Safest mode.
  • No affiliate links, nothing to buy. Each fact links to its primary source, with the date we checked it.
  • They cannot tell you that your seed is safe. No tool can do that by looking at your words, and any site that offers to "check" them is a scam.

Also here

  • Security advisories: known problems with wallets and wallet software, with a link to each maker's own page.
  • Corrections log: every fix we make to a published page, with its date.

Check yourself

A website says it can check whether your seed was affected by a flaw if you type in your 24 words. What do you do?

Close it. No real check needs your words, and anyone who has them can take your bitcoin. To see whether an advisory applies to you, answer questions about your device instead, as in Was my seed affected by the 2026 Coldcard flaw?

You are about to make a new seed with dice. Which tool helps, and what comes before it?

How many dice rolls do I need? But your device's own dice instructions come first: each maker uses dice in its own way.

Can any of these tools tell you that your seed is safe?

No. They explain, count, and walk you through checks you do yourself, offline. A tool that claimed to judge your seed would need your words, and that is exactly what you should never give.