Since version 1.9.0, you can use Drag-and-Drop to copy or move files between Amazon S3 Accounts and Buckets.

This feature can be useful when you need to copy or move files between Amazon S3 Accounts without mounting an external bucket.

Let's assume you have two Amazon S3 Accounts: account1, registered under email acc1@domain.com and account2, registered under email acc2@domain.com and you want to copy files from account1 to account2.

1. Start S3 Browser, switch to account1, select the bucket that contains files you need to copy, and give READ access to account2. See article How to share an Amazon S3 Bucket with another AWS user(s) for more details. Skip this step if you want to copy/move files between buckets that are in the same Amazon S3 Account.
2. 
   Start second instance of S3 Browser, switch to account2 and select the bucket that you want to use as destination.
3. 
   Drag-and-Drop files from account1 to account2 to copy these files. Hold the SHIFT key if you want to move these files.
   Use Drag-and-Drop to copy/move files between Amazon S3 buckets.
4. 
   S3 Browser will start copying or moving files and will refresh the files list when all files are processed.