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).

Header type Request header
Forbidden header name no

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 compatibility

DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Early-Data
Experimental
Chrome ? Edge ? Firefox Full support 58IE No support NoOpera ? Safari ? WebView Android ? Chrome Android ? Firefox Android Full support 58Opera Android ? Safari iOS ? Samsung Internet Android ?

Legend

Full support
Full support
No support
No support
Compatibility unknown
Compatibility unknown
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.