Based on what you've said here: >"Went through one company which lead me on with first a phone >interview then a hacker rank challenge then a take home >project then a onsite interview with a whiteboard programming >challenge and a final interview. I never heard back from >them, only to find out later on that I had been rejected >without them telling me!"

I would suggest you could have a couple of issues (bearing in mind that I have little evidence to go on):

1. One might be technical competency - The only time I'll repeatedly give technical questions i.e. HackerRank, TakeHome, Whiteboard is if I'm not convinced that you have the technical skill by some earlier stage.

2. You're failing the "cultural fit" test. This is in my opinion always the hardest one to figure for an interviewer, and is usually the last question hanging over a candidate. I understand that you're frustrated with the process, but any semblance of arrogance during an interview is often a big negative in the post interview recap. Particularly if the position is more commodity than specialist developer.

To add more context can you do any or all of the following; - Post some code - What sort of position are you going for? - Where are you based?