Ad networks that seem to support browser targetting:
Client - Useragent: this will enable you to target ads to matching
strings, which includes information about the user's browser/operating
You can target line items to a user’s browsing environment:
Bandwidth: cable, DSL, etc.
Browser: Android, Chrome, Firefox, Google Chrome, Microsoft Internet
Browser language: Chinese, English, Italian, German, etc.
If a browser has more than one language assigned to it, each language
will generate an impression. In reports, you will see a higher number
of impressions attributed to "browser language" than what's shown for
total impressions for the line item. Operating system: Android, Apple
iOS, Linux, Macintosh, Microsoft Windows, etc.