ETag

Entity tag for the resource. Used with If-None-Match for conditional requests and caching.

Response

Syntax

ETag: [W/]<tag>

Example values

ValueExplanation
"33a64df551425fcc55e4d42a148795d9f25f89d4"Strong ETag
W/"0815"Weak ETag

cURL usage

curl -I https://api.example.com/users/1  # Get ETag

Common mistakes

Using weak ETag for byte-for-byte comparison; cache busting issues.

Related headers

Tools

HTTP Header Viewer →