Air-gapped, zero-leak diagnostic utility. Compute 24th-word checksum candidates, detect mistyped dictionary words, and repair transposed mnemonics entirely in local browser memory via WebCrypto.
🔒 Air-Gap Security Protocol
This file is completely self-contained. It contains no analytics, no remote dependencies, and no phone-home telemetry.
For distressed production seeds: disconnect your Wi-Fi, enable Airplane Mode, or run this file from a USB flash drive on a computer without network hardware.
Calculate Valid 24th Words
Enter 23 BIP-39 words. The tool uses native SHA-256 to calculate the exact 8 words that satisfy the 8-bit checksum.
Typo & Missing Word Solver
Enter 24 words. If a word is illegible, use ?. If the checksum fails, the tool scans all 24 positions for closest spelling matches (Levenshtein distance).
24-Word Integrity & Checksum Inspector
Live word verification, dictionary lookup, 11-bit indices, and SHA-256 entropy check.
📋 How to Use This Tool Safely with Large Distressed Funds
Save this page by pressing Ctrl+S (or Cmd+S) to a clean USB flash drive.
Plug the USB drive into an air-gapped laptop or reboot your current machine with Wi-Fi / Bluetooth disabled.
Open the saved .html file in any modern browser (Chrome, Brave, Firefox, Safari).
Verify that network activity is 0 (open DevTools Network tab — there will be 0 requests).
Find your typo or calculate the missing 24th word.
Transcribe the corrected word onto your physical recovery sheet with pen and paper.
Close the browser, power down the air-gapped machine, and verify on your physical hardware wallet screen.