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Date

IANA permanent response RFC 9110 2 spellings

Declared by 35 providers across 2422 published specification files in the APIs.io network.

What this header is for, and how to use it →

A count here is providers whose published contract declares this header — not providers who send it. Response headers set at the edge rarely appear in an OpenAPI at all, so a low number can measure documentation practice rather than deployment.

Spelled 2 ways

HTTP field names are case-insensitive (RFC 9110 §5.1), so every spelling below is the same header on the wire. A contract is not the wire: generated clients key off the string, and a developer reading two of these sees two different headers.

Datedate

The registry

Status	permanent
Reference	RFC 9110, Section 6.6.1: HTTP Semantics

Providers declaring it (35)

aimlapi api-pulse apiops-cycles-canvas bird bitpowr-technologies-inc brightcove chaitin conekta deliverect extreme-networks finix finix-payments fintecture hipay infisical linkedin london-stock-exchange-group messaging-api microsoft-azure orders-api persons-api products-api salesforce shopback shyft streamelements tetrascience tribe-payments unified-to upwind upwind-security userpilot vtex xflow zoominfo

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