Arq is backup software for Mac and Windows that stores encrypted, versioned backups wherever you choose, from your own cloud account to an external drive or NAS.

Key features:

Back up to your own cloud storage, an SFTP server, an external drive or a NAS, or several at once.
Encrypt backups end to end so only you can read them.
Make point-in-time backups using filesystem snapshots, even while files change.
Restore earlier versions after corruption, deletion or ransomware.
Save space with compression, de-duplication and block-level incremental backups.
Skip backups on certain Wi-Fi networks or on battery, and limit bandwidth.

Arq 7 is $59.99 per computer, a one-time purchase with one year of updates and optional update years after that. Arq Premium is $69.99 a year for five computers with 1 TB of included storage and web access. A 30-day free trial is available, and backups use an open, documented format.