A Dev
Door (or Developer
Door) is a level creator resource in the Super Mario romhacking community, and in the Super Mario Maker community intended to provide a more prompt and direct access to sections of a level of considerable length that are intended to be reached through the regular route in the final product. Mainly used during the developing stages of a level, Dev doors allow the editor to reach a part of the level that would otherwise take a long time to reach if they
play the level from the very start
point.
Dev doors became a necessity in Super Mario Maker in particular, as the game only allows for
two checkpoints per level, while doors are unlimited. Ideally, dev doors should be removed, or hidden at the very least, before the level is published, and the presence of a dev
door in a published level indicates a lack of oversight and
polish by the level creator.