gsutil
The gsutil tool is "an open-source command-line utility available for Windows, Linux, and Mac.
• "Multi-threaded/processed: Useful when transferring large number of files.
• "Parallel composite uploads: Splits large files, transfers chunks in parallel, and composes at destination.
• "Retry: Applies to transient network failures and HTTP/429 and 5xx error codes.
• "Resumability: Resumes the transfer after an error."