In the fast-evolving world of programmatic advertising, efficiency and transparency are key to maximizing revenue for publishers. One of the most widely adopted solutions for header bidding is Prebid, an open-source framework that enables publishers to integrate multiple demand sources and optimize competition for their ad inventory.
At Start.io, we’re committed to ensuring seamless participation in the programmatic ecosystem by developing Prebid adapters—both client-side (Prebid.js) and server-side (Prebid Server). In this article, we’ll explore what Prebid is, why it’s crucial for modern ad monetization, and the differences between client-side and server-side integrations.
What is Prebid?
Prebid is an open-source set of software solutions that simplify header bidding, allowing publishers to connect with multiple demand partners in a fair, real-time auction before making an ad request to their primary ad server.
By leveraging Prebid, publishers increase competition for their ad inventory, achieve higher eCPMs, reduce latency and improve page load speeds, and gain access to analytics and auction insights.
Prebid offers two main ways to integrate with demand sources: client-side (Prebid.js) or server-side (Prebid Server). Each offers its own advantages, depending on the publisher’s needs.
Client-side vs. server-side Prebid adapters: Key differences
As we develop adapters for both Prebid.js (for client-side auctions) and Prebid Server (for server-side auctions), it’s important to understand how they differ.
| Feature | Prebid.js | Prebid Server |
| Auction location | Runs in the user’s browser | Runs on a separate server |
| Latency | Can be slower due to multiple network calls from the browser | Faster, as bidding happens server-side |
| Transparency | Publishers have full visibility into bids | Less transparent due to server-side processing |
| User syncing | More control over cookies and user data | Limited access to cookies due to privacy restrictions |
| Implementation complexity | Easier to set up | Requires infrastructure for server management |
| Data privacy | Subject to browser limitations (ITP, Privacy Sandbox, etc.) | Less affected by browser restrictions |
What is Prebid.js?
Prebid.js runs directly in the user’s browser, sending bid requests from the publisher’s page to multiple demand sources. The browser selects the highest bid and passes it to the ad server for final decisioning.
- Pros: Higher transparency, better cookie matching, easy set up
- Cons: Increased latency, browser restrictions (e.g. Apple ITP, Google Privacy Sandbox)
Server-side Prebid
In contrast, Prebid Server offloads the auction process to a server, reducing the number of network calls from the browser. Instead of handling bids in the client environment, the request is sent to Prebid Server, which communicates with multiple demand partners and returns the highest bid.
- Pros: Lower latency, better scalability, reduced impact from browser privacy restrictions
- Cons: Reduced transparency, weaker user ID matching, requires server infrastructure
Why Start.io is building Prebid Adapters
At Start.io, we are laser-focused on helping publishers maximize their ad revenue opportunities, across both client-side and server-side environments.
By developing Prebid.js adapters, we’re helping publishers participate in real-time auctions directly within the browser. Meanwhile, our Prebid Server adapter helps publishers who would rather participate in real-time auctions using server infrastructure.
By supporting both integration methods, we’re providing flexibility for publishers to choose the right setup based on their needs: Prioritizing transparency with client-side bidding, or speed and efficiency with server-side auctions.
Prebid has become a cornerstone of programmatic ad monetization, offering publishers greater control, competition, and transparency in header bidding. Understanding the differences between Prebid.js and Prebid Server is crucial for choosing the right approach to ad monetization.
Stay tuned for more updates as Start.io expands its capabilities in the Prebid ecosystem. Contact us today to learn more about how we can help you optimize your ad monetization strategy with Prebid adapters.
