Unveiling the Phantom Visitors: A Guide to Detecting Bot Traffic in Google Analytics and BigQuery

22nd May 2024

5 Minutes Read

By Anshul Dhurandhar

In the vast realm of website analytics, data integrity is paramount. But lurking within the shadows can be a deceptive foe: bot traffic. These automated bots can inflate website traffic metrics, skewing data and hindering your ability to make informed marketing decisions. This blog equips you with the knowledge and tools to identify and combat bot traffic in Google Analytics (GA4) and BigQuery, ensuring your data reflects genuine user interactions.

Why Detecting Bot Traffic Matters

Bot traffic can have a significant negative impact on your website analytics:

  • Data Distortion: Inflated website traffic figures paint an inaccurate picture of user engagement. This can lead to misinformed marketing strategies and resource allocation.

  • Attribution Errors: Bots can trigger conversions and events, skewing attribution models and making it difficult to understand which marketing channels are truly driving results.

  • Wasted Resources: Resources spent on seemingly high traffic from bots can be better directed towards attracting and engaging real users.

  • Security Risks: Some bots can be malicious, attempting to steal data, inject malware, or disrupt website functionality.

Identifying Bot Traffic: The Telltale Signs

While not always foolproof, several red flags can indicate the presence of bot traffic:

  • Unusual Traffic Patterns: Look for sudden spikes or dips in traffic, particularly outside of regular business hours. Bots often operate around the clock.

  • Low Time on Site and Bounce Rate: Bots typically spend minimal time on your website and bounce quickly after landing on a page.

  • Referrals from Unknown Sources: A surge in traffic from unknown or suspicious referral sources might be a sign of bot activity.

  • Implausible Geographic Locations: An influx of traffic from geographically inconsistent locations can be a red flag, especially if your target audience is limited to a specific region.

  • Strange User Activity: Bots might exhibit repetitive actions like clicking on specific elements or navigating through your website in an unnatural way.

Leveraging GA4 for Bot Detection

GA4 offers built-in functionalities to help you identify bot traffic:

  • IP Filtering: Create filters to exclude known bot IP addresses from your reports. While not exhaustive, this can eliminate some basic bot activity.

  • Custom Dimensions and Metrics: Define custom dimensions to capture data points like user agent strings or screen resolution. Analyze these dimensions to identify patterns indicative of bot behavior.

  • Engagement Reports: Analyze reports that measure user engagement, such as time on site and scroll depth. Bots typically exhibit minimal engagement, providing valuable insights.

Unveiling the Depths with BigQuery

For a more granular analysis, consider exporting your GA4 data to BigQuery, Google's cloud data warehouse. BigQuery allows you to perform advanced queries and uncover hidden patterns in your website traffic data. Here's how:

  1. Export GA4 Data to BigQuery: Set up a data export from GA4 to BigQuery to create a centralized repository of your website traffic data.

  1. Identify Bot Activity: Leverage BigQuery's powerful SQL capabilities to analyze user behavior data and identify anomalies. Explore metrics like time on site, session duration, and clickstream data to detect patterns suggestive of bots.

  1. User Agent Analysis: Extract and analyze user agent data within BigQuery. Bots often have unique user agent strings that deviate from those used by typical browsers.

  1. IP Geolocation: BigQuery allows you to join your website traffic data with geolocation data sets. This can help identify suspicious traffic originating from unexpected locations.

Beyond Detection: Taking Action Against Bot Traffic

Once you've identified bot traffic, it's crucial to take action:

  • Block Known Bot IPs: Maintain a list of known bot IP addresses and block them at the firewall level to prevent further access.

  • Implement Security Measures: Utilize CAPTCHAs or other verification methods to deter automated bots from accessing forms or completing actions on your website.

  • Monitor Continuously: Bot activity can evolve, so stay vigilant. Regularly monitor your website traffic for suspicious patterns and adapt your detection strategies accordingly.


Combating bot traffic is an ongoing battle. By employing a combination of GA4's built-in features and the power of BigQuery, you can gain valuable insights into your website traffic and identify bots masquerading as real users. Remember, a data-driven approach coupled with continuous monitoring is key to maintaining the integrity of your website analytics and making informed marketing decisions.