Mountain Duck supports opening and reverting previous versions of files. You can get a list of previous versions by right-clicking on a file in Finder on macOS or File Explorer on Windows and choosing Versions.
Support is currently limited to connections to Amazon S3 with buckets that have versioning enabled.
You can open a previous version of a file by choosing Versions → … → Quick Look. This will open a Quick Look preview on macOS or open the previous version of the file in the defailt application on Windows.
You can revert to a previous version of a file by choosing Versions → … → Revert. Wait for the File Updated notification which notifies the previous version has been restored.