Free Backup Software
Daptin
With Daptin you can build faster, more capable APIs over your data that works across all types of frontend. Daptin is a free and open-source headless CMS server written in Go. Daptin can be used as a backend for both mobile and web applications and provide ready-to-go REST and GraphQL API infranstructure.
CloudBuckIt
One desktop application to manage all your cloud storage accounts and FTP connections. Simply connect your cloud profiles and acess them from your local computer just like any other file. CloudBuckIt integrates with Google Drive, Dropbox, Mega, OneDrive, Flickr, Amazon Cloud Drive, FTP, Box, Picasa, SugarSync, Yandex, EverNote, My pCloud and many other cloud solutions.
Perkeep
Perkeep is a set of free and open-source formats, protocols, and software for modeling, storing, searching, sharing and synchronizing data in the post-PC era. Data may be files or objects, tweets or 5TB videos, and you can access it via a phone, browser or FUSE filesystem. Perkeep is openly and actively developed and anyone is free the contribute to the project.
Yandex.Disk
Yandex.Disk is a free cloud service provided by Yandex. The software lets you store, backup and sync files in the cloud by dragging and dropping them into the browser window or via the mobile application. Yandex.Disk can be used for batch operations on files and folder, and allows the user to publish images to the web. The software is available for Android, iOS, macOS, Linux, Windows, Windows Phone and the web browser.
Nextcloud
With Nextcloud, users can host their own secure cloud solution for file storage, collaboration and communication for enterprise or personal purposes. Nextcloud gives you full control over your own data and where and how you host it. The software can be hosted on-premise or on any VPS or cloud instance provided by third-party web hosts. If you value privacy and security, Nextcloud might be the right choice for you. Nextcloud is both free and open source and developed in an open, transparent and trustworthy manner.
SparkleShare
SparkleShare is a free and open-source cloud storage and file synchronization software. By default SparkleShare uses Git as a storage backend and creates a special folder on your computer that you can add remotely hosted folders (directories). Projects in this folder will automatically stay synced with the host and its peers. When someone add, remove or edit files within a project, syncronization happens across peers. SparkleShare can be used with hosted services such as GitHub, but can also be hosted on your own server for more control.
Syncthing
Syncthing is a free and open-source continuous file synchronisation software that utilise peer-to-peer technology. The software allows users to send files between two or more computers in real time, safely protected from prying eyes. Syncthing is available for Windows, Mac, Linux, Android, Solaris, and BSD.
carotDAV
With CarotDAV you can manage multiple cloud based service from a single application. CarotDAV supports syncronization with WebDAV, FTP, Microsoft OneDrive, Dropbox, Google Drive, Box, and SugarSync. CarotDAV is available work Microsoft Windows.
Transmission
Transmission is a file sharing application that utilize torrent techonlogy. The software provides UPnP and NAT-PMP port forwarding and features you come to expect from torrent applications like web seed support, watch directories, tracker editing, global and per-torrent speed limits, and much more.
S3 Browser
S3 Browser is a file management application designed to be used in tandem with Amazon.com's web-based storage, Simple Storage Service or the S3 protocol. With S3 Browser, you can upload your files to the S3 services and manage them much like an FTP client.