What snakes don't lay eggs?

There are lots of snakes that don't lay eggs - they hold the eggs inside their bodies until they hatch, it's not placental like with mammals, but it's often called live birth and the clutches are often referred to as litters. Most boa species (with only 2-3 species that lay eggs), garter snakes, copperheads, and some vipers are a few examples of these types of snakes.