File Extension UPLOAD File Format upload file UPLOAD stands for upload file. This was last updated in March 2012 By Margaret Rouse Browse File Extensions Alphabetically: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ask a Question. Find an Answer. Ask your peers a question about this file extension. Ask a Question File upload security best practices: Block a malicious file upload Autocad-PDF Chapter 15 -- Handling file uploads -- of 'Beginning PHP and MySQL 5'