Buying traffic · also called whitelist, inclusion list
Allowlist
An allowlist is a list of approved websites, apps or placements, with ads permitted to run only on those and nowhere else.
An allowlist reverses the logic of a blocklist. Instead of "run everywhere except these", it says "run only here". Nothing new gets in until someone has checked it.
In search arbitrage an allowlist is usually the second stage of a campaign's life. First the buyer runs widely on a small budget to discover which placements produce engaged visitors and clean, finalised revenue. Then the proven ones are copied into an allowlist campaign that receives the larger budget. Because every source is known, quality is steadier and there are fewer surprises from the feed.
The price is reach. Fewer placements mean fewer clicks available, more competition for them, and often a higher CPC, which limits scaling. Placements also change over time, so an allowlist needs re-checking. Advertisers use the same idea on the other side of the market: some run search ads only on Google or Bing itself and decline partner sites altogether, the choice described under advertiser opt-out.
Think of it like this
It is a guest list at the door. A blocklist turns away known troublemakers; an allowlist admits only people whose names are written down.
Related terms
Blocklist
A blocklist is a list of websites, apps or placements where a buyer tells an ad network never to show their ads.
Placement
A placement is the specific website, app, section or screen position where an ad appears.
Scaling
Scaling is increasing a profitable campaign's ad spend to earn more total profit, ideally without eroding the return that made it worth growing.
Advertiser opt-out (search partners / parked domains)
Advertiser opt-out is an advertiser's ability to stop its search ads appearing on partner sites, and in 2025 to 2026 on parked domains, outside the search engine itself.
Traffic quality score
A traffic quality score is a rating of how genuine and commercially valuable a publisher's visitors are, used to decide what their clicks are paid, or whether to keep them.