COMPLETE GUIDE

How to Use Zefer

Complete guide to encrypt and decrypt files with Zefer.

Get started now

No installation needed. Zefer works directly in your browser.

Open Zefer Web

Encrypt

01

Select text mode or file mode

02

Enter your content or drag a file

03

Set a passphrase (minimum 6 characters)

04

Configure expiration, compression, and security level

05

Download the .zefer file

Decrypt

01

Upload or drag a .zefer file

02

Enter the passphrase

03

Answer the security question if required

04

View or download the decrypted content

Advanced Features

Reveal key: share a different password with recipients while keeping your main passphrase private.

Dual passphrase: require two different passwords to decrypt (two-person authorization).

Secret question: add an extra authentication step with a PBKDF2-hashed answer.

IP restriction: limit decryption to specific IPv4/IPv6 addresses.

Max attempts: limit the number of decryption tries.

Compression: reduce file size with Gzip or Deflate before encryption.

URL Parameters

Pre-configure forms via URL for workflow automation.

Use tab/t to select tab: /?tab=encrypt or /?t=decrypt

passphrase / p

Main passphrase (minimum 6 characters)

passphrase2 / p2

Second passphrase (auto-enables dual key)

dual / d

Enable dual key mode (1 or true)

reveal / r

Reveal key for the recipient

mode / m

Input mode: text or file

ttl

Expiration in minutes (0=never, 30, 60, 1440, 10080, 20160)

security / s

PBKDF2 level: standard, high, maximum

compression / c

Compression: none, gzip, deflate

hint / h

Public hint (visible without passphrase)

note / n

Public note (visible without passphrase)

question / q

Security question

answer / a

Security question answer

attempts / att

Max decryption attempts (0=unlimited)

ips

Allowed IPs comma-separated (IPv4/IPv6)

Sensitive parameters (passphrase, passphrase2, reveal, answer) are automatically removed from the URL after reading.

# Decrypt

/?t=decrypt&p=myKey123

# Encrypt

/?t=encrypt&m=file&ttl=30&c=gzip&s=high

# Advanced Features

/?t=encrypt&p=key1&p2=key2&q=Color%3F&a=blue&ips=10.0.0.1,192.168.1.5

Self-Hosting

Clone the repository

git clone https://github.com/carrilloapps/zefer.git && cd zefer

Install dependencies

npm install

Build the project

npm run build

Start the server

npm start

HTTPS is required for the Web Crypto API to work.

How to use the CLI

All of Zefer from your terminal with zefer-cli. Files are 100% compatible with the web.

Install the CLI globally from npm — or run it without installing via npx zefer-cli

npm install -g zefer-cli

Encrypt any file or text with your passphrase

zefer encrypt secret.txt -p "passphrase"

Decrypt .zefer files, including those created on the web

zefer decrypt secret.txt.zefer -p "passphrase"

Generate secure keys, analyze passwords, and inspect files without a passphrase

zefer keygen · zefer analyze · zefer info file.zefer

Start the built-in MCP server for AI agents

zefer mcp

The CLI also exposes all of its capabilities as an MCP server. More details at MCP

Integrate with AI Assistants

Zefer publishes a /llms.txt file following the llmstxt.org standard so AI assistants can understand the project automatically.

Claude Code

Claude Code automatically reads CLAUDE.md and llms.txt. Clone the repo and run claude at the project root.

git clone https://github.com/carrilloapps/zefer.git && cd zefer && claude

GitHub Copilot (VS Code / CLI)

GitHub Copilot Chat in VS Code or CLI can use llms.txt as context. Use @workspace with a reference to the file.

@workspace /explain #file:llms.txt

Cursor / Windsurf / Augment

Cursor, Windsurf, and similar editors read CLAUDE.md and .cursorrules automatically. The llms.txt can be added as a context file.

For any LLM or AI tool, pass the URL as context.

https://zefer.carrillo.app/llms.txt
Install Zefer