All HTTP Status Codes
503

Service Unavailable

5xx Server Error

What It Means

The server is currently unable to handle the request due to temporary overloading or maintenance.

When You'll See It

Returned during planned maintenance or when the server is overloaded. Often includes Retry-After.

Related Status Codes

502 Bad Gateway 504 Gateway Timeout 429 Too Many Requests

Frequently Asked Questions

What does HTTP 503 mean?

HTTP 503 Service Unavailable means: The server is currently unable to handle the request due to temporary overloading or maintenance.

When does a server return 503?

Returned during planned maintenance or when the server is overloaded. Often includes Retry-After.

Is 503 a client error or server error?

HTTP 503 is a Server Error (5xx) response. This means the issue is on the server side — the server failed to fulfill a valid request.

Looking for all status codes in one place? Use the interactive HTTP Status Codes reference tool to search and browse all codes.