There are, in fact, dozens of them, some of the many years old. There are so many, there are guides to choosing the right one.
Some, like Battlegrounds, are extremely good at handling any flavor of d20 systems, and are very, very easy to learn to use. Some, like Roll20, are less versatile, but have free versions, and run in a browser and are thus truly (as) cross-platform (as anything can be). And some, like MapTool, are completely free, with an active support community that is very user friendly, and a macro language that can do virtually anything if you work at it.
This is yet another attempt by Hasbro to turn tabletop gaming into computer gaming, which demonstrates, yet again, that they have absolutely no clue what tabletop gaming is, or what the appeal is, but they know that there are people with money they aren't giving to Hasbro, and dammit! that's not acceptable!