What is Quantcastbot?
Direct Answer: Quantcastbot is a web crawler used by Quantcast for advertisement quality assurance and to understand page content for Interest-Based Audiences.
Quantcastbot is a web crawler used by Quantcast for two main purposes: advertisement quality assurance and understanding page content for Interest-Based Audiences. For quality assurance, it checks advertisements to ensure they meet creative specifications. For Interest-Based Audiences, it crawls a daily selection of 2-5 million websites to extract page content and help categorize audience interests.
User-Agent Identification
The following user-agent strings identify Quantcastbot in your live traffic data:
Quantcastbot/1.0 (+http://www.quantcast.com/bot)
robots.txt Rules for Quantcastbot
Respects robots.txt: No
Use the following robots.txt rules to control Quantcastbot access:
# Block Quantcastbot
User-agent: Quantcastbot
Disallow: /
# Allow Quantcastbot
User-agent: Quantcastbot
Allow: /This bot does not commit to following robots.txt
Quantcastbot does not officially follow robots.txt directives. The only reliable way to control access is through server-side blocking (IP filtering, user-agent rules in your web server config) combined with log monitoring to verify effectiveness.
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Crawl Behavior
Frequency:Continuous, With A Rate Limit Of About 1000 Urls Per Day
Request Pattern:Crawls A Daily Selection Of 2-5 Million Web Sites For Interest-Based Audiences, And Visits Landing Pages Of Advertisements For Quality Assurance
Official Documentation Quotes
"Quantcast Bot is the name of a web crawler used by Quantcast for advertisement quality assurance and to understand page content for Interest-Based Audiences."
"Quantcast’s QA technology will not access your website unless Quantcast is trafficking advertisements that click through to your website."
"When Quantcast crawls web sites to understand page content, we do honor disallows for either the specified url or the full domain on robots.txt."
Crawl Activity Index
Relative crawl activity for Quantcastbot over the past 28 days. Higher values indicate increased crawling intensity compared to the period baseline.
View recent activity data (last 7 days)
| Date | Activity Index |
|---|---|
| Mar 28, 2026 | 4.3 |
| Mar 29, 2026 | 5.5 |
| Mar 30, 2026 | 7.5 |
| Mar 31, 2026 | 7.5 |
| Apr 1, 2026 | 4.8 |
| Apr 2, 2026 | 6.9 |
| Apr 3, 2026 | 2.2 |
Source: Cloudflare Radar
Why track Quantcastbot traffic?
Verify ad system crawling behavior. Quantcastbot evaluates your pages for ad targeting, quality scoring, and policy compliance.
Optimize ad delivery. If Quantcastbot can't properly access certain pages, ad targeting and revenue may be impacted. Log monitoring confirms accessibility.
Log Verification
To verify Quantcastbot traffic in your live traffic data:
- Search access logs for the user-agent strings listed above
- Check if the IP addresses match documented ranges (if provided by Quantcast)
- Verify the crawl pattern matches documented behavior
- Use reverse DNS lookup for additional verification if available
Note: Observed behavior in production environments may differ from official documentation. Live traffic monitoring provides the only reliable verification of actual bot behavior.
Undocumented Information
The following information is not officially documented for Quantcastbot:
- JavaScript rendering
Official Documentation
View Official Quantcastbot Documentation →
Information sourced from official documentation. Content generated with AI assistance.