Ever since binge-watching 13 Reasons Why, we've been highly emotional. While there are several shocking twists in the final episode, the biggest cliffhanger is Alex's fate. In episode 12, a 17-year-old is rushed to the hospital for a gunshot wound to the head, and in the next episode, Principal Bolan reveals to Mr. Porter that it was Alex. Even though some people seem to think Tyler is the one who pointed the gun, we have reason to believe the wound was actually self-inflicted.
As first pointed out by BuzzFeed, Alex becomes increasingly depressed throughout the series, and one of his last scenes is a dead giveaway that he tries to shoot himself: he cleans his room. You know who else does this household chore? Hannah, right before she slits her wrists in the bathtub. While this doesn't seem like a big deal at first glance, it's actually a warning sign for suicide. People contemplating killing themselves will often "get their affairs in order" by tidying their room or giving away personal possessions, much like Hannah returns her work uniform before heading home.
I guess all we can do now is patiently wait for Netflix to announce a second season so we can finally get some answers.