Question 1

What is Zefer?

Accepted Answer

Zefer is a free, open-source tool that encrypts text and files into password-protected .zefer files using AES-256-GCM. Everything happens in your browser — no server ever stores, processes, or transmits your data. You can share the encrypted file through any channel, and only someone with the passphrase can open it.

Question 2

Is Zefer free to use?

Accepted Answer

Yes. Zefer is completely free and open source under the MIT license. There are no accounts, no subscriptions, no ads, and no usage limits. You can also self-host it or use the official zefer-cli command-line tool.

Question 3

Is Zefer secure and private?

Accepted Answer

Zefer uses AES-256-GCM authenticated encryption with PBKDF2-SHA256 key derivation (up to 1,000,000 iterations). It is zero-knowledge and 100% client-side: passphrases and keys never leave your device, there are no cookies or trackers, and security metadata (expiration, IP limits, secret question) is sealed inside the encrypted payload, not the public header.

Question 4

Do I need an account to use Zefer?

Accepted Answer

No. Zefer requires no account, no email, and no sign-up. Open the site, type or upload your content, set a passphrase of at least 6 characters, and download the encrypted .zefer file instantly.

Question 5

What is a .zefer file and how do I open it?

Accepted Answer

A .zefer file is a portable, password-protected encrypted file that contains your content along with the salt and IV needed for decryption. To open it, upload it back to Zefer (or use zefer-cli) and enter the correct passphrase. Without the passphrase the file is completely unreadable.

Zefer: Share secrets securely

Encrypt a secret

How it works

Resources & documentation

Zefer: Share secrets securelyZeferShare secrets securely

Encrypt a secret

How it works

Resources & documentation

Zefer: Share secrets securely