Twitter ads conversion tracking code.
https://business.twitter.com/en/help/campaign-measurement-and-analytics/conversion-tracking-for-websites.html
Analytics and Tracking · Conversion Optimization
Get access to data on 598,264 websites that are Twitter Conversion Tracking Customers. We know of 114,881 live websites using Twitter Conversion Tracking and an additional 483,383 sites that used Twitter Conversion Tracking historically and 77,463 websites in the United States.
Get a list of 598,264 websites using Twitter Conversion Tracking which includes location information, hosting data, contact details, 114,881 currently live websites and an additional 584,469 domains that redirect to sites in this list. 483,383 sites that used this technology previously and 77,463 websites in the United States currently using Twitter Conversion Tracking.