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Early-Data

This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The Early-Data header is set by an intermediary to indicate that the request has been conveyed in TLS early data, and also indicates that the intermediary understands the 425 (Too Early) status code.

The Early-Data header is not set by the originator of the request (i.e., a browser).

Syntax

Early-Data: 1

Examples

GET /resource HTTP/1.0
Host: example.com
Early-Data: 1

Specifications

Specification Title
RFC 8470, section 5.1: The Early-Data Header Field Using Early Data in HTTP

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
Early-Data ? ? 58 No ? ?
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
Early-Data ? ? 58 ? ? ?

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Early-Data