nimbril
Privacy

Encrypt any file with a password — on your device

Drop in any file, set a password, and get back a locked .nbenc you can store or send anywhere. It's real AES-256-GCM encryption with a 210,000-round PBKDF2 key stretch, so a weak guess can't brute its way in.

Because every step runs in your browser, your file and your password never leave your device. Nothing is uploaded, retained, or transmitted — flip on airplane mode and it still encrypts and unlocks.

Live tool · your files stay on this device
Loading Encrypt

How it works

1
Drop in your file

Pick any file — a contract, a scan, a spreadsheet — and choose a strong password. It loads straight into the browser tab, with no upload step and no account.

2
Lock it with AES-256

nimbril encrypts on your device using AES-256-GCM, deriving the key from your password with a 210k-round PBKDF2 stretch. You download a sealed .nbenc file.

3
Unlock anytime

Drop the .nbenc back in and enter the password to recover the original, byte for byte. The password is never stored or sent — only you can open it.

Frequently asked

Are my files uploaded when I encrypt them?

No. Encryption runs entirely in your browser. Your file and your password never leave your device — nothing is uploaded, stored, or transmitted to any server. You can turn off wifi and it still works.

Is it free, and what does Pro cost?

Yes, there's a generous free tier you can use with no signup. Pro is $9/mo or $69/yr and unlocks batch encryption, ZIP export, unlimited history across all nimbril tools, or $4/mo for just this app.

What encryption does it use?

AES-256-GCM, the same authenticated cipher trusted for sensitive data. Your key is derived from your password with a 210,000-round PBKDF2 stretch, which makes password-guessing attacks far slower.

What happens if I forget the password?

The file can't be recovered. Because nothing is uploaded and the password is never stored anywhere, there's no reset or backdoor — keep your password safe.

How do I open an encrypted file later?

Drop the .nbenc file back into the tool and enter the password. It decrypts on your device and returns the exact original file. Anyone with the password and the tool can unlock it offline.