A Tool to Resize and Crop Images

You can build a website that helps people resize and crop images.

Here is an example:

https://imageresizer.com/

How to Build Something Better

You can enable users to crop and resize in one click rather than resizing then cropping. It's a minor thing but it makes all the difference.

How to Monetize

You can run display ads or charge users for cropping multiple images at once.