AI engineering glossary · Web APIs HTTP
What is 503 Service Unavailable?
503 Service Unavailable: The status code meaning the server cannot handle the request right now, typically due to overload or maintenance. It is temporary, and may include Retry-After to say when to try again.
503 Service Unavailable: an example
An overloaded model API replies 503 during a traffic spike.
Related terms
More Web APIs HTTP terms
Where you learn it
503 Service Unavailable is part of the AI Engineering Program, which teaches it with notes, a hands-on lab and an exam. The first lesson is free.