Horizon Send is described as 'Secure file sharing service that uses XChaCha20 end-to-end zero-knowledge encryption to protect your files' and is a large file transfer service in the file sharing category. There are more than 50 alternatives to Horizon Send, not only websites but also apps for a variety of platforms, including Windows, Linux, Mac and Android apps. The best Horizon Send alternative is LocalSend, which is both free and Open Source. Other great sites and apps similar to Horizon Send are Send, pCloud, Hoodik and WeTransfer.