All tools

HTTP Retry-After Header Builder

Network

Build a Retry-After response header from a delay in seconds or a target date/time, or parse an existing one, per RFC 9110

Build a Retry-After response header from either a plain delay in seconds or a target date and time, the header a 429 Too Many Requests or 503 Service Unavailable response uses to tell a client when it is safe to try again. A date is automatically formatted as the HTTP-date syntax the header actually requires, since a raw ISO string is not valid there. Paste an existing Retry-After value into the parser to see whether it is a seconds-delay or an HTTP-date, and get the equivalent ISO timestamp back either way.

retry-afterhttpheadersrfc9110rate-limitingrest-api

How to use HTTP Retry-After Header Builder

  • 1.Pick whether to build from a plain delay in seconds or a target date/time.
  • 2.Enter the seconds to wait, or a date/time string, and copy the generated header value.
  • 3.Paste an existing Retry-After header into the parser field to see its type (seconds or HTTP-date) and normalized value.

Frequently asked questions

Why can't I just put an ISO date string directly in the header?
The Retry-After header only accepts two formats per RFC 9110: a plain integer number of seconds, or an HTTP-date in the IMF-fixdate format (e.g. "Wed, 21 Oct 2026 07:28:00 GMT"). This tool converts whatever date string you enter into that exact format.
Which format should I use, seconds or a date?
Seconds is simpler and is what most rate-limit responses use. A target date is more useful when the retry time is tied to a specific scheduled event, like a maintenance window ending at a known time.
Does this tool check what time it actually is right now?
No, it only formats or parses the value you give it. It does not compute a delay from the current time or make any assumption about your server's clock.
Does this make a network request?
No, it only builds or parses the header value locally. It does not send a request or check what a real server returns.

Use via API, SDK, or MCP

cURL# Free: 1,000 req/day · Pro: 10,000 req/day
curl -X POST https://api.utilix.tech/v1/tools/retry-after-builder \
  -H "Authorization: Bearer utx_live_..." \
  -H "Content-Type: application/json" \
  -d '{"seconds":120,"date":"2026-10-21T07:28:00.000Z","header":"Retry-After: 120"}'

Get an API key from your dashboard · Full API docs →

Related tools

HTTP Prefer Header (RFC 7240) Parser / BuilderBuild an HTTP Prefer request-header value from a list of preferences with optional values and parameters, or parse an existing one, per RFC 7240NetworkAccept-Language Header Parser / BuilderBuild an Accept-Language request-header value from locale/quality pairs, sorted by preference, or parse an existing header into its ranked locale/quality entriesNetworkCache-Control Header BuilderBuild and explain an HTTP Cache-Control response header from directives like max-age, s-maxage, no-store, and immutableNetwork