Alt-SendMe — Serverless Peer-to-Peer File Transfer

Introduction

Alt-SendMe is an open-source file transfer tool that sends files and folders directly between any two devices using encrypted peer-to-peer connections. It requires no cloud accounts, has no file size restrictions, and supports resumable transfers over the QUIC protocol.

What Alt-SendMe Does

• Transfers files of any size directly between devices without cloud intermediaries
• Encrypts all data in transit using BLAKE3 hashing and modern cryptography
• Supports resumable transfers that continue after network interruptions
• Uses NAT hole-punching and QUIC for fast peer-to-peer connectivity
• Provides both CLI and desktop GUI interfaces via Tauri

Architecture Overview

Alt-SendMe uses the QUIC protocol for fast, multiplexed transfers with built-in encryption. Connection establishment leverages hole-punching techniques to traverse NATs without requiring port forwarding. Files are chunked and hashed with BLAKE3 for integrity verification. The desktop app is built with Tauri and React for a lightweight cross-platform UI.

Self-Hosting & Configuration

• Install the CLI binary or download the desktop app for your OS
• No server setup required; connections are direct peer-to-peer
• Configure relay servers as fallback when hole-punching fails
• Set bandwidth limits and concurrent transfer caps in preferences
• Transfer codes are one-time use and expire after completion

Key Features

• No file size limits and no cloud storage involved
• End-to-end encryption with BLAKE3 and modern cipher suites
• Resumable transfers that survive network drops
• Cross-platform: Linux, macOS, Windows via Tauri desktop app
• No accounts, sign-ups, or third-party dependencies

Comparison with Similar Tools

• Magic Wormhole — similar P2P concept but slower protocol, no resume support
• croc — P2P file transfer in Go, similar but less modern protocol stack
• WeTransfer — cloud-based, 2GB free limit, requires browser
• ShareDrop — WebRTC-based, limited to same network or small files
• OnionShare — uses Tor for anonymity, slower due to onion routing

FAQ

Q: Do both parties need the app installed? A: Yes. Both sender and receiver need the Alt-SendMe CLI or desktop app.

Q: Is there a file size limit? A: No. Files of any size can be transferred directly between peers.

Q: What happens if the connection drops mid-transfer? A: Transfers are resumable. Re-run the receive command to continue from where it stopped.

Q: Does it work across different networks? A: Yes. NAT hole-punching allows connections across most network configurations.

Sources

• https://github.com/tonyantony300/alt-sendme