Rclone is a file synchronization tool that features built-in support for several dozen cloud storage providers. These include both large providers like Amazon S3 and Microsoft OneDrive, as well as self-hosted solutions like ownCloud and NextCloud. Rclone can operate in one of three modes. In copy mode, any new or changed files are uploaded. In sync mode, Rclone makes a destination folder identical to a source folder, deleting files if necessary to do so. Finally, in check mode, Rclone will report the differences between two folders. Rclone is able to operate entirely over the network, without the need for a local folder. For example, it can synchronize an Amazon S3 bucket with a Box.com folder. The optional crypt plugin allows users to transparently encrypt data before uploading it and can be used as part of an encrypted offsite backup strategy. Extensive usage information is available on the docs section of the Rclone website. Rclone executables can be downloaded for Windows, macOS, Linux, and several other types of UNIX. Rclone is free software, distributed under the MIT license, with source code available on GitHub.