Quantcast has partnered with Liveramp to ingest third-party audiences. Third-party segments are best used to complement Quantcast audiences and should be viewed as a backup option when internal audience creation isn't sufficient for your needs.
Any custom / ad-hoc requests should go through Liveramp. Please do not reach out to individual data providers.
LiveRamp
Liveramp: Accounts in the US and targeting the US can now target three providers: Bombora, D&B, and Experian. These three providers offer both Lookalike and Retargeting options.
Third-party segments are best used as a complement to Quantcast audiences and should be viewed as a backup option when internal audience creation isn't sufficient for your needs.