One of my favorite free fraction apps is Oh No Fractions. Students must determine whether the fraction on the left is greater than, less than, or equal to the fraction on the right. I like that it gives the option of showing a visual model of the fractions if needed.
When starting a fraction unit, I always try to start with a solid foundation in finding factors and multiples as well as identifying prime/composite numbers. This foundation is crucial when it comes time for comparing and simplifying fractions. Here’s a FREE prime/composite number sort with self-checking QR codes.