alt-sendme

alt-sendme is an open-source desktop app that enables direct file transfers between devices. It removes the need for cloud storage by establishing peer-to-peer connections, allowing users to send files and folders of any size or format without creating accounts or providing personal information. This approach ensures that data moves directly from the sender to the receiver rather than being uploaded to a third party server.

The application is available for Windows, macOS, and Linux, with an Android version also provided. Users initiate a transfer by dropping a file or directory into the app to generate a one-time share code, known as a ticket. This ticket contains the necessary cryptographic identity information for authentication. Once the sender shares this ticket via chat, email, or text, the recipient pastes it into their own app to begin the download process.

Key features

• Peer-to-peer direct transfers without cloud storage
• End-to-end encryption using QUIC and TLS 1.3
• BLAKE3-based integrity checks for files and directories
• Resumable downloads for interrupted transfers
• NAT traversal via QUIC hole punching with encrypted relay fallback
• Broadcast mode to share files with multiple peers
• Interoperability with the Sendme CLI
• Support for self-hosted relays for increased privacy

Built with Tauri and React, the software uses the Iroh networking stack to handle content-addressed blob storage and peer discovery. It utilizes Ed25519 NodeIds for cryptographic authentication and implements a ticket system to form secure networks between specific peers. This architecture allows the software to saturate multi-gigabit connections while maintaining privacy by avoiding the broadcast of IP addresses to unknown peers. The system uses BLAKE3 hashes to identify blobs, ensuring that the data received is identical to the data sent.

For users with specific privacy requirements, the software allows the deployment of custom relays via Docker Compose. By configuring both the sender and receiver to use the same self-hosted relay, users can bypass public infrastructure entirely. This makes the tool suitable for professional environments or privacy-conscious individuals who need to move large datasets across different networks without relying on corporate cloud ecosystems.

This tool is a privacy-focused utility for users who require secure, direct file sharing without the restrictions or data collection associated with centralized cloud providers.