Last-Modified

Last-Modified is an HTTP header a web server can send alongside a page or file, declaring when that content last changed. For example:

Last-Modified: Tue, 07 Jul 2026 14:32:00 GMT

Browsers use it for caching, and crawlers - including search engines and Silktide - use it as a signal of how current the content is.

It is only as reliable as the server that sends it: some servers report the time the page was served rather than when its content genuinely changed, so Silktide treats it as one signal among several. Declared dates inside the page, such as structured data, are usually more trustworthy.

Learn more

• HTTP header fields - the RFC 9110 specification
• HTTP header
• Structured data