A door closer manufacturer is a company or other fabricator which assembles devices which close doors automatically. Door closers are fairly small mechanical devices, usually affixed both to a door and to a neighboring wall, which use pressure or electric power to push a door back to a closed position after it has been opened. These may be used to maintain fire safety, basic security, or internal climate control.

The closer is a device fitted to the door and its surroundings. Its function is to return the door to the closed position after opening, whether the purpose is fire safety, security, or control of internal conditions.

An automatic door manufacturer supplies doors that open when people approach. Automatic closing and automatic opening are different functions, and fitting a closer alone does not provide approach-operated opening.