What Quantcastbot does
Quantcastbot is Quantcast's web crawler and serves two functions. For quality assurance, it checks that advertisements meet creative specifications before delivery, visiting only ad landing pages; this QA traffic triggers impression and click trackers, and Quantcast says it should be excluded from traffic counts as non-human. For Interest-Based Audiences, it analyzes site content, extracting titles, descriptions, headers, and paragraph text across 2 to 5 million websites daily to categorize audience interests, rate-limited to roughly 1,000 URLs per day per site spread over several hours. It identifies itself as Quantcastbot/1.0 or Quantcastbot/2.0 with a link to quantcast.com/bot.
How to control Quantcastbot
Target Quantcastbot in your robots.txt with the Quantcastbot token. Rules apply per bot, so you can allow this one while blocking others, or the reverse.
Allow Quantcastbot
User-agent: Quantcastbot
Allow: /Block Quantcastbot
User-agent: Quantcastbot
Disallow: /Quantcast publishes the specific IP addresses legitimate Quantcastbot requests originate from, and only its Interest-Based Audiences crawling respects robots.txt, while its ad quality assurance crawling of ad landing pages ignores robots.txt.
How to identify Quantcastbot
Temso identifies Quantcastbottraffic by matching the request's User-Agent header against this pattern. User-agent strings can be spoofed, so treat a match as an indication, not proof.
QuantcastbotQuantcastbot FAQ
What is Quantcastbot?
Quantcastbot is Quantcast's web crawler. It validates that ads meet creative specifications before delivery and analyzes website content to categorize audience interests for Quantcast's Interest-Based Audiences advertising.
How do I block Quantcastbot?
Add a robots.txt group with User-agent: Quantcastbot and Disallow: / (or Allow/Disallow rules for specific paths). This only affects its Interest-Based Audiences content crawling; Quantcast's documentation states the quality assurance crawling of ad landing pages ignores robots.txt, so blocking that traffic requires filtering by its published IP addresses instead.
About Advertising Bots
Bots run by ad platforms to check landing pages, verify ad placements, and analyze content for brand safety and targeting.
If you run ads on a platform, its ad bots usually need access; blocking them can break ad approval and quality checks for your own campaigns.
