ETag & conditional request playground
Set up a resource with an ETag and Last-Modified date, then send conditional GET headers. See whether the server should return200 OK with a body or 304 Not Modified — all in the browser.
Strong validators
Weak validators
Resource (origin)
Computing SHA-256…ETag = quoted first 16 hex chars of SHA-256.
Resource ETag
HTTP-date (GMT)
Request (client cache revalidation)
Supports *, a single tag, or a comma-separated list. Weak comparison on GET.
IMF-fixdate or any datetime string the browser can parse.
Result
Response headers
No validator headers to show.
Sample HTTP response
Shareable URL keeps weak/manual mode only — not the resource body. Everything runs in the browser.
About this tool
Browsers and CDNs reuse cached responses when validators still match. A conditional GET sendsIf-None-Match and/or If-Modified-Since; the origin compares them to the current resource and either returns304 Not Modified (no body) or a fresh 200 OK.
When both headers are present, If-None-Match wins. On GET, ETag comparison is weak — soW/"abc" matches "abc" if the opaque tag is identical.