From what I've seen (I live in LA) it's much more driven by Silicon Valley companies opening up offices down here than by locally originated start-ups, though there are of course many exceptions.
Which ones have offices in LA? Do you recommend any of them? I'm looking to move down there myself.
I know Google and Amazon do but LinkedIn, Uber, Square, and Facebook don't.
Snapchat is headquartered in LA. Microsoft, Oracle, Netflix, and Symantec also have large offices. Riot, Activision, SpaceX, Dollar Shave Club, EA, Hulu, True car, Buzzfeed, Telesign, Spokeo, Tinder, eHarmony, and MAXCDN are the major tech companies in LA that I can think of off the top of my head
Unless you're looking to get into tech related to entertainment LA is a backwater compared to the Bay Area.