# What Are Freshness Signals?

How websites tell crawlers what has changed

![Charles Vayssié, founder of Scrubnet](https://scrubnet.org/charles-vayssie.webp)

By [Charles Vayssié](https://scrubnet.org/about-us.html)

Founder, Technical SEO & Web Developer

Technical SEO specialist and web developer leading strategy and delivery across complex e-commerce and international websites, with expertise in migrations, rendering, crawl management, structured data and Core Web Vitals.

You update a guide today. A crawler may still have yesterday’s copy. Freshness signals help readers and bots tell when content changed and check whether a copy they already have is still current.

Published 9 November 2026

## Where do freshness signals appear?

Imagine a guide published on 14 September 2026 and substantially revised on 6 October 2026.

### XML sitemap

An XML sitemap lists page URLs. The ``<lastmod>`` value gives the date of a particular page’s last significant update. Use the date the guide actually changed, even if you regenerate the sitemap later. Google says it uses this value when it is consistently accurate and verifiable. [Google’s sitemap guidance](https://developers.google.com/search/docs/crawling-indexing/sitemaps/build-sitemap#xml-sitemap)

````xml
<url>
  <loc>https://example.com/guide</loc>
  <lastmod>2026-10-06</lastmod>
</url>
````

### Visible dates and structured data

A reader might see **Published 14 September 2026** and **Updated 6 October 2026**. JSON-LD can carry those same dates as ``datePublished`` and ``dateModified``. Google considers page dates alongside other clues when deciding which date to show in search results. [Google’s guidance on page dates](https://developers.google.com/search/docs/appearance/publication-dates)

````json
{
  "@context": "https://schema.org",
  "@type": "Article",
  "datePublished": "2026-09-14",
  "dateModified": "2026-10-06"
}
````

### HTTP response headers

``Last-Modified`` gives the server’s modification date for the version it serves. ``ETag`` gives that version a tag. A crawler can send back the date in ``If-Modified-Since`` or the tag in ``If-None-Match`` to check its saved copy. [Google’s crawler caching documentation](https://developers.google.com/crawling/docs/crawlers-fetchers/overview-google-crawlers#http-caching)

````http
Last-Modified: Tue, 06 Oct 2026 10:00:00 GMT
ETag: "guide-v2"
````

## How might bots use them?

A crawler might use a sitemap date to decide which pages to revisit sooner. If a bot sends a conditional request and its saved copy is still current, the server can return ``304 Not Modified`` without sending the page body again. The bot still makes a request, but there is less data to transfer. [HTTP specification](https://www.rfc-editor.org/rfc/rfc9110.html#section-15.4.5)

## What do we still not know?

For many bots, we still don’t know which signals they use, if any, or how much those signals affect when they come back. Server logs can show when a verified bot visited and what the server returned. Establishing why it chose that URL, or whether the page was later indexed or cited, takes separate evidence.

Scrubnet’s first Freshness Observatory results offer an example of what crawler request logs can reveal. [Freshness Signals vs Crawl Reality](https://scrubnet.org/discoveries/freshness-signals-vs-crawl-reality.html)

## How to check freshness signals with SEO Scrubbox

1. Open the page in Chrome and click SEO Scrubbox. Under **Freshness Signals**, look for the page dates and the ``Last-Modified`` header found by the quick check.
2. In **Cache & Compression**, the **Validator** row shows whether the audit found an ``ETag``.
3. Select **Run Deep Checks**. If the audit finds a ``<lastmod>`` value for that URL in a checked sitemap, it appears under **Freshness Signals**.

![SEO Scrubbox Freshness Signals report showing a conflict between the structured data update date and the Last-Modified header](https://scrubnet.org/discoveries/seo-scrubbox-freshness-signals-audit.webp)

Get the extension from the [SEO Scrubbox page](https://scrubnet.org/seo-scrubbox.html).