How do date and last_updated differ in Perplexity search results?

Definition: In Perplexity's Search API, date is the publication date of a result page, while last_updated is the date that page was last updated. Both are optional fields in each result.

Key facts

• Perplexity's Search API reference places date and last_updated in each ranked results[] item alongside the title, URL, and snippet.
• The reference describes date as the page's publication date and last_updated as the date the page was last updated.
• Google's Article structured data documentation defines datePublished as the first publication date and dateModified as the most recent modification date, both in ISO 8601 format.
• Schema.org defines datePublished as the date of first publication or broadcast and dateModified as the date on which a CreativeWork was most recently modified.

What do the two fields mean?

Perplexity returns a ranked results[] array. In each result, date and last_updated are optional fields, so a result can have one, both, or neither in the response. The reference assigns a different meaning to each field: publication belongs to date; the latest page change belongs to last_updated.

The response shape looks like this in the documentation:

{
  "date": "2025-01-23",
  "last_updated": "2025-09-25"
}

The two values describe the source page's timeline. They are not two names for the same event. A page first published on one date can later receive an update, leaving the publication date earlier than the last update date.

How do the API filters relate to the fields?

Perplexity documents separate filters for publication and update time. search_after_date_filter and search_before_date_filter filter by publication date. last_updated_after_filter and last_updated_before_filter filter by update date. The API also has search_recency_filter, whose documented values are hour, day, week, month, and year.

The request properties are named explicitly in the Search API schema:

{
  "query": "example topic",
  "search_after_date_filter": "MM/DD/YYYY",
  "last_updated_after_filter": "MM/DD/YYYY"
}

The same schema specifies MM/DD/YYYY as the input format and YYYY-MM-DD as the output format for its date type. A publication filter therefore asks for pages published after a boundary, while an update filter asks for pages updated after a boundary.

Which website metadata corresponds to each field?

For an article page, Google's structured data guidance maps datePublished to the date and time the article was first published. It maps dateModified to the date and time the article was most recently modified. Google recommends ISO 8601 and timezone information for both properties.

Schema.org gives the same distinction at the vocabulary level. Its datePublished property covers first publication or broadcast. Its dateModified property covers the most recent modification of a CreativeWork or an entry in a DataFeed. Keeping these values semantically separate gives a publisher two fields that correspond to the two meanings Perplexity exposes.

The Perplexity reference defines the result fields and filters, but it does not identify a particular HTML tag or structured-data property as the input it uses to produce them.

What should you check on a page?

Inspect the page's structured data and compare the values with the visible publication and update information. Google shows the following JSON-LD pattern in its Article documentation:

{
  "@type": "Article",
  "datePublished": "2024-01-05T08:00:00+08:00",
  "dateModified": "2024-02-05T09:20:00+08:00"
}

The example includes timezone offsets. Google also documents Article, NewsArticle, and BlogPosting as the schema.org types for its Article feature, and lists datePublished and dateModified as recommended properties. For an API consumer, retain the distinction when storing a result: map the publication concept to date and the latest-update concept to last_updated.

Related terms

• Perplexity
• Can Perplexity search be restricted to recent sources?
• Perplexity Sonar
• Article update dates

FAQ

Is last_updated the date Perplexity retrieved the page?

The Search API reference defines it as the date the page was last updated. It does not label the field as a retrieval timestamp.

Should you replace datePublished when an article changes?

No. datePublished represents first publication, while dateModified represents the most recent modification. Preserve the publication date and change the update date when the page is modified.

Can you filter publication date and update date separately?

Yes. The API documents search_after_date_filter and search_before_date_filter for publication boundaries, plus last_updated_after_filter and last_updated_before_filter for update boundaries.

Sources

1. Perplexity, "Search the Web", 2026-09-28
2. Perplexity, "Search the Web", 2026-09-28
3. Google Search Central, "Article structured data", 2026-09-08
4. Schema.org, "datePublished", undated
5. Schema.org, "dateModified", undated

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