kitchenaid k400 blender jar leaking from the bottom when i blend, did i crack it?

Unlikely a crack. The seal is compromised.

DIAGNOSIS: The jar isn't fully seated on the base or the gasket is worn.

FIX:

1. Unplug the blender.
2. Remove the jar and dry everything.
3. Place and align the jar with the slot on the jar pad. The jar handle must face the control dial.
4. Press down firmly until you feel it click into place.

IF THAT DIDN'T WORK: If it still leaks, inspect the rubber gasket/seal around the blade assembly at the bottom of the jar. It may need replacement.

HEADS UP: Never move or carry the blender by the jar. Always lift from the base. Carrying it by the jar can disengage the base and damage the seal.