Depending on what type of cake you are making, your oven temperature, and the procedure you followed when you mixed the cake batter, there are a variety of reasons why a cake might crack or split on top.
Video of the Day
If a cake isn't placed in the center of an oven rack, it's more likely to crack or split on top. To ensure even baking, place all cakes as close to the center of the rack as possible.
An oven that's too hot can cause a cake to crack. The sides of the cake will bake more quickly than the center, so the center has extra time to peak and then crack. To prevent this from happening, line the sides of the pan with parchment paper or grease them thoroughly.
If some ingredients are too cold, the cake may crack and prevent air bubbles from forming and a proper rise from happening. Wait until eggs, butter, and other refrigerated ingredients are at room temperature before mixing.
A cake is more likely to crack if its top and sides are baking at different rates. Try to achieve even baking by greasing cake pans well and placing them in the middle of the oven instead of near the heating element.
An overmixed batter can result in a cracked cake. Try mixing ingredients just until they're combined.
Batter Too Wet
A batter with too many liquid ingredients is more likely to create a cracked cake. Make sure liquids are proportional to dry ingredients before baking.