Altersend

Product Introduction

1. Definition: Altersend is a peer-to-peer (P2P) file transfer application and protocol designed for direct, end-to-end encrypted (E2EE) data exchange between devices. It falls into the technical categories of decentralized networking and privacy-focused software.
2. Core Value Proposition: It exists to provide a truly private, cloud-free, and frictionless method for transferring files of any size between any platforms. Its primary value is enabling secure P2P file sharing without mandatory accounts, cloud storage intermediaries, or artificial file size limits.

Main Features

1. Peer-to-Peer, End-to-End Encrypted Transfers: Files stream directly from the sender's device to the receiver's device over the internet. The connection uses the ChaCha20-Poly1305 encryption algorithm, generating new session keys for each transfer. No file data is ever stored on a central server or cloud storage.
2. Zero-Account, Code-Based Pairing: Users initiate transfers by scanning a QR code or sharing a short join code. This pairs devices without requiring email sign-up, username creation, or account management. For trusted devices (like your own laptop and phone), pairing is permanent, allowing future transfers without re-entering codes.
3. Cross-Platform with No Size Caps: The software is open-source and provides native applications for macOS, Windows, Linux, iOS, and Android. The P2P protocol imposes no file size limits, supporting transfers from a few kilobytes to hundreds of gigabytes, as the data is streamed, not uploaded to a capped cloud bucket.

Problems Solved

1. Pain Point: Reliance on insecure or inconvenient middlemen for file sharing. Traditional methods involve uploading files to cloud storage (creating a copy and privacy risk), requiring accounts, or being restricted by network constraints (like Apple AirDrop's Wi-Fi/Bluetooth limitation) and platform lock-in.
2. Target Audience: Privacy-conscious individuals, professionals handling sensitive data (lawyers, journalists, developers), users with limited cloud storage, multi-platform households, and anyone needing to send very large files that exceed email or free cloud service limits.
3. Use Cases: Securely sending confidential documents between a Windows PC and an Android phone; transferring a large 4K video project from a Mac to a Linux desktop without intermediate upload/download steps; quickly sharing a folder of photos from an iPhone to a friend's Windows laptop over the internet.

Unique Advantages

1. Differentiation: Unlike WeTransfer (cloud storage), AirDrop (platform-locked, network-limited), LocalSend (local network only), or Magic Wormhole (CLI-only, uses a readable relay), Altersend combines internet-wide reach, full cross-platform support, a graphical user interface (GUI), and a strict no-cloud-storage architecture.
2. Key Innovation: Its "pair once" architecture for trusted devices. While initial pairing uses a code for security, subsequent transfers between known devices are automatic. Only a public device key is stored for identification; the private secret remains secured in the operating system's native keychain (e.g., macOS Keychain, Windows Credential Manager), streamlining the user experience while maintaining security.

Frequently Asked Questions (FAQ)

1. Is Altersend truly free and open source? Yes, Altersend is completely free to use with no hidden fees or tiers, and its source code is publicly available on GitHub for audit and verification, ensuring transparency about its security and privacy claims.
2. How does Altersend work without an internet connection? Altersend requires an internet connection to establish the initial peer-to-peer connection between devices, as it is designed for internet-wide transfers. For offline, local network transfers, tools like LocalSend may be more appropriate.
3. Where are my files stored during an Altersend transfer? Your files are never stored on any server. They exist only on the sender's device, are encrypted in transit, and are written directly to the receiver's device. There is no cloud storage backend, eliminating the risk of server-side data breaches.
4. Can I use Altersend to send files to someone in a different country? Yes, Altersend works over the public internet. As long as both devices have an internet connection and can establish a direct or relay-assisted P2P connection, geographical distance is not a barrier to transfer.
5. What happens if the transfer is interrupted? As a streaming P2P tool, an interrupted transfer would typically need to be restarted. The protocol does not currently support resumable transfers, as there is no intermediate cloud storage to hold a partial file.