425 Too Early

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

The HTTP 425 Too Early client error response status code indicates that the server was unwilling to risk processing a request that might be replayed to avoid potential replay attacks.

If a client has interacted with a server recently, early data (also known as zero round-trip time (0-RTT) data) allows the client to send data to a server in the first round trip of a connection, without waiting for the TLS handshake to complete. A client that sends a request in early data does not need to include the Early-Data header. See Early-Data for more information.

Status

http
425 Too Early

Specifications

Specification
Using Early Data in HTTP
# status

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
425

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
No support
No support
See implementation notes.

See also