People love Griddy
$.99 or hire a designer
First of all, I used to have a designer split images into grids. Now that I have my own business I don't really have a dedicated resource or the budget to keep asking someone to do this in top of photo shoots and marketing ops costs.
Effective and Simple
The app automates splitting pictures quickly into multiple rows. I just got it and was impressed how quickly and easily it works.
Great for making your posts more noticeable especially if you are trying to gain folllowers