Built-in, builtin, or built in may refer to:

• Shell builtin, a command or a function executed directly in the shell itself
• Builtin function, in computer software and compiler theory

• Built-in behavior, of a living organism
• Built-in furniture
• Built-in inflation, a type of inflation that results from past events and persists in the present
• Built-in obsolescence, in industrial design and economics
• Built-in self-test, a mechanism that permits a machine to test itself
• Built-in stabiliser, in macroeconomics

• All pages beginning with "built-in", "builtin" and "built in"
• All pages with titles containing "built-in", "builtin" and "built in"
• Built (disambiguation)
• Bulletin (disambiguation)