Thanks for reaching out to us!
When you save your image, you’ll notice (on web/desktop) you can see the file size. You can reduce this, by either reducing the quality (in the quality slider) or by reducing the image’s width and height. This can all be achieved from the Save screen and you’ll see the new file size before you save.
If you have any further questions, please let us know!
– Regards, The Ribbet Team