There are 13 games in the Kingdom Hearts timeline.
Kingdom Hearts HD 1.5 and 2.5 ReMix Guide - IGN
Kingdom Hearts: Birth by Sleep Review
Sora and IGN by jojo56830 on DeviantArt
Kingdom Hearts - IGN
Kingdom Hearts 358/2 Days - IGN
Every IGN Kingdom Hearts Review So Far
What the Kingdom Hearts 1.5 + 2.5 ReMix Titles Actually Mean - IGN
Kingdom Hearts II - IGN
How to Play the Final Fantasy Games in Order - IGN
Kingdom Hearts [V Cast Mobile] - IGN
Kingdom Hearts - IGN
If you've played them, it makes sense that that's the order they happened in. : r/Gamingcirclejerk
Walkthrough - Kingdom Hearts 3 Guide - IGN
To anyone who may be here to figure out where to start, do not follow this article's advice : r/KingdomHearts