The only technical challenge that their process claimed to use was a TripleByte test, which was broken up into three different areas: Front-end, General Logic, and Backend. The tests are multiple-choice.

I did well in everything except the Front-end test, which oddly asked a lot of questions about web-sockets (which I have little-to-no experience with).

Most notable about the process that I noticed was how easy it would have been to cheat on the tests. (They make you 'agree' not to use web searches for answers), which seems like a major flaw in the system.

I also suspect that, as a result, Rocket Mortgage inevitably winds up hiring people that were willing to cheat on the test.

The general logic test (among other things) has you interpret code blocks to anticipate the results and/or to 'finish the logic'.