Strongsync is described as 'Dropbox-like Sync and Backup using only SFTP or Amazon S3' and is an app in the Backup & Sync category. There are more than 10 alternatives to Strongsync for a variety of platforms, including Online / Web-based, Windows, iPhone, Mac and Android. The best alternative is Dropbox, which is free. Other great apps like Strongsync are Microsoft OneDrive (Freemium), Koofr (Freemium), SugarSync (Paid) and Filestash (Freemium, Open Source).
Koofr is a safe, secure and simple way to store, backup and share your documents, photos, videos and more. It offers up to 10GB of free safe storage for your files with affordable upgrades and options to connect multiple cloud accounts.
CopyBucket is a cloud-based clipboard. It gives you the power of cloud-storage with the ease of use of copy/paste. Add items in buckets using copy/paste or drag-n-drop. Items appear on your other devices. Create new buckets and keep related items together.
Synology C2 synchronizes data across all your devices, such as computers, mobile devices, or other Synology NAS. Build a private cloud and ensure files are readily available when and where you need them.