Prebid.js is an open-source header bidding solution that gives you control over how demand partners compete for your inventory. Getting the configuration right has a direct impact on fill rate, CPMs, and page performance. The following best practices apply regardless of which bidders you're running.
Keep your Prebid.js build lean
Only include the bidder adapters you're actively using in your Prebid.js build. Every adapter adds weight to your bundle, which increases page load time. A bloated build slows down your auction before it even starts — and slower auctions mean more timeouts and lost revenue.
Set an appropriate auction timeout
Your timeout setting determines how long Prebid waits for bid responses before sending what it has to the ad server. Too short and you'll cut off legitimate bids; too long and you risk ad latency that hurts user experience and viewability.
Most publishers find a timeout in the 1000–3000ms range to be a reasonable starting point. Sovrn recommends monitoring your bidder response times and setting your timeout to accommodate the majority of responses without waiting on chronic slow responders.
Use price granularity that matches your CPMs
Prebid maps bid prices to key-values sent to your ad server using price granularity settings. If your granularity buckets are too coarse, higher bids get rounded down and you leave revenue on the table. Make sure your price granularity configuration covers the CPM range your inventory actually commands — and consider custom granularity if the built-in options don't fit your pricing tier.
Enable user ID modules selectively
Prebid's user ID modules can improve match rates and CPMs by passing persistent identifiers to demand partners. However, each module adds latency and may have consent implications. Only enable the ID modules that your active demand partners actually support, and make sure your CMP is configured to gate them appropriately under GDPR and other applicable privacy frameworks.
Pass first-party data
Demand partners bid higher when they have context about your content and audience. Use Prebid's ortb2 configuration to pass first-party data — such as content category, page topic, or audience segments — at the auction level. This data travels with every bid request and can meaningfully improve CPMs without requiring changes to individual bidder configs.
Monitor bid metrics regularly
Prebid Manager and your ad server reporting can surface where you're losing value — whether that's timeouts, low bid rates from specific partners, or price granularity gaps. Treat your Prebid configuration as a living setup that needs regular tuning, not a one-time implementation.
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