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
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Early-Data | Chrome ? | Edge ? | Firefox Full support 58 | IE No support No | Opera ? | Safari ? | WebView Android ? | Chrome Android ? | Firefox Android Full support 58 | Opera 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.