Whatever your goal with this question is, keep in mind:
Age ist not an achievement.
19. I created an online app that led to Microsoft licensing the underlying bits from my lab. I also helped present it to what was then Live Labs.
I was an employee at my lab; so, I didn't have any rights to royalties and such, but I was well compensated.
At age 24 I generated over $100k in a year and again the following year with a game editor. Notably it was 1994 and I was selling through BBS and mail-order mostly.
Hmm, 17 and AT&T licensed a little meta-search engine I wrote to put onto the front page of "AT&T WorldNet", which I think was their answer to AOL.
Started at 16, wasn't an "app", but was an online business that generated more than enough money.