# ZapTransfer

## Purpose
ZapTransfer is a secure file transfer service that enables users to share files with end-to-end encryption.

## Key Features
- **End-to-end encryption**: Files are encrypted in the user's browser before upload. Encryption keys never leave the client.
- **Zero-knowledge architecture**: The server never has access to unencrypted files or encryption keys.
- **Temporary storage**: Files automatically expire and are deleted after a configurable period (default 7 days).
- **Password protection**: Optional additional password protection for shared files.
- **No registration required**: Anonymous file sharing without user accounts.
- **100MB file size limit**: Supports file transfers up to 100MB.

## How It Works
1. User selects files to transfer (drag & drop or file picker)
2. Files are encrypted client-side using WebCrypto API (AES-GCM)
3. Encrypted files are uploaded to the server
4. Server stores encrypted files temporarily in Cloudflare R2
5. User receives a shareable link with the encryption key in the URL fragment
6. Recipients use the link to download and automatically decrypt files in their browser

## Security Model
- Client-side encryption using AES-256-GCM
- Encryption keys are generated client-side and never sent to the server
- Keys are shared via URL fragments (not sent in HTTP requests)
- Optional password protection adds an additional layer of security
- Files are automatically deleted after expiry

## Privacy
- No user tracking or analytics
- No cookies except essential session management
- Files are deleted permanently after expiry
- No logs of file contents or encryption keys
- Minimal metadata retention (file size, upload date, expiry)

## Use Cases
- Secure document sharing for businesses
- Private file transfers between individuals
- Temporary file hosting for collaboration
- Sensitive data exchange without cloud storage accounts

## Contact
For support or questions, please visit https://zaptransfer.xyz/support