Offline BIP39 Tool

One HTML file with the generator, validator, converter, checksum and word list. Download it, check its hash, and open it with networking off.

Current release

File
bip39-ai-offline-v0.1.0.html
Version
0.1.0 · commit 211d6ed
Size
305.5 KB (312,873 bytes)
Built
2026-09-24
SHA-256
d2d6e032f42cc79c4ca99b3b97e136fb16b8456b620006499ac33b2d45b95516

1. Verify the download

Compute the file’s SHA-256 and compare it with the value above. They must match exactly.

macOS or Linux

shasum -a 256 bip39-ai-offline-v0.1.0.html

Windows (PowerShell)

Get-FileHash .\bip39-ai-offline-v0.1.0.html -Algorithm SHA256

If they differ, delete the file and do not open it.

2. Use it offline

  1. Turn off Wi-Fi and unplug network cables (or use airplane mode).
  2. Open the file by double-clicking it, or drag it into a browser window. It opens as a file:// page.
  3. Check the badge at the top reads Offline build v0.1.0.
  4. When finished, close the tab and browser before reconnecting.

Consider a private/incognito window: most browsers disable extensions there unless you have allowed them.

3. Confirm there are no network requests

  1. Open developer tools (F12, or ⌥ ⌘ I on macOS) and select Network.
  2. Reload the page and use each tool.
  3. The list should contain only the file itself. The file’s Content Security Policy also blocks connections, which you can read in its first lines.

Release evidence

ItemStatus
SHA-256 publishedYes on this page
Official test vectorsPass 24/24 English vectors, checked on every build
Independent implementation cross-checkPass 120 cases vs python-mnemonic 0.21
Source tag for this releasev0.1.0
Reproducible buildNot yet available
Signed releaseNot yet available
Independent security auditNot yet available

Limitations

  • It cannot protect against an infected computer, malicious browser extensions, screen recording or clipboard monitoring.
  • Clearing a field resets the page, but JavaScript cannot guarantee every copy is erased from memory. Close the browser when done.
  • It does not derive private keys or addresses and cannot recover wallets.

Frequently asked questions

Why not just use the website with Wi-Fi off?

That helps, but the code still came from a server at that moment. A downloaded file can be checked against a published hash, kept, and reused — so you know exactly which code is running.

Does the offline file protect me from malware?

No. If the computer is compromised, malware can read the screen, keyboard or clipboard. For real funds, a dedicated clean device or a hardware wallet is safer.

Which browsers does it work in?

Current versions of Chrome, Edge, Firefox and Safari. It needs JavaScript and the Web Crypto API, which modern browsers provide even for local files.

Is the hash on this page enough to trust the file?

It proves the file matches what this page publishes. If an attacker controlled this website, they could change both. Compare the hash with the one in the source repository release as a second, independent channel once that is available.