Soda PDF has two different ways that you can review two documents next to each other.
Using the Compare Documents feature, found in the Review Module, you will find our track changes feature. This is best used when comparing different versions of the same file. Any changes made will be highlighted. Click here to learn more.
Our Side By Side View option lets you simply open up two files next to each other. There are no markings to indicate changes in the document. You can find this in the View Module. Click here for more information.