Retry-After
The HTTP Retry-After response header indicates how long a client needs to wait before making a follow-up request.
Usage
The Retry-After header appears in responses where the server needs the client to delay before retrying. The header is commonly paired with three status codes:
- 503 Service Unavailable: the server is temporarily down for maintenance or overloaded. The Retry-After value signals when the service expects to be available again.
- 429 Too Many Requests: the client exceeded a rate limit. The Retry-After value tells the client when the rate limit window resets.
- 3xx redirect: a scheduled redirect where the server suggests a minimum wait time before the client follows the redirect.
The header accepts two formats: a delay in seconds (delta-seconds) or an absolute HTTP-date. When using seconds, the value is a non-negative integer representing the number of seconds to wait. When using an HTTP-date, the value follows the IMF-fixdate format.
Well-behaved clients and crawlers honor this header to avoid overwhelming a recovering server.
Note
Search engine crawlers treat Retry-After on 503 responses as a signal to revisit the URL later rather than removing the page from the index. Googlebot and Bingbot both respect this header to schedule return visits. During planned maintenance, returning 503 Service Unavailable with Retry-After preserves indexability. Without the header, prolonged downtime risks deindexing.
Values
Delta-seconds
A non-negative integer specifying the number of seconds the client needs to wait before retrying the request.
Retry-After: 120
HTTP-date
An absolute date and time in IMF-fixdate format after which
the client is free to retry. The date uses GMT and follows the
format Day, DD Mon YYYY HH:MM:SS GMT.
Retry-After: Sat, 31 Oct 2026 18:00:00 GMT
Example
A server responding with 503 during a maintenance window tells the client to wait 3600 seconds (one hour) before retrying.
HTTP/1.1 503 Service Unavailable
Retry-After: 3600
An API rate limiter responding with 429 provides an absolute date when the rate limit resets. The client pauses requests until the specified time.
HTTP/1.1 429 Too Many Requests
Retry-After: Sat, 31 Oct 2026 12:30:00 GMT
A scheduled redirect with 301 includes a delay to prevent immediate retry storms from multiple clients.
HTTP/1.1 301 Moved Permanently
Location: https://new.example.re/resource
Retry-After: 60
Takeaway
The Retry-After response header specifies a waiting period before the client retries, expressed as a delay in seconds or an absolute date. Servers send the header with 503, 429, or any 3xx redirect response to manage client retry behavior and protect service availability.