Looking to outsource a tool that I need for myself, and will sell to others. It has to do with image manipulation. What would you guys have it coded in?

Trying to decide if I make the tool available inside a membership site, or make it a standalone tool that a user downloads.

Personally, it does not matter for my use. Web-based, stand alone does not affect my use. But if I am going to sell this to other mobile app developers, just trying to consider the best technology, lowest cost to have coded and ease of maintenance.

Input appreciated.