Prebid Server: Understanding Prebid’s Server-side Header Bidding

Server-side header bidding is key to reducing latency and improving scalability in programmatic advertising. While Google’s Open Bidding and Amazon’s UAM offer proprietary solutions, they often lack transparency and control.

Prebid Server, an open-source alternative, addresses these issues with transparency, flexibility for custom setups, and community-driven improvements. However, it comes with challenges like complex implementation and potential reliance on third-party providers, which may limit visibility and introduce data inconsistencies.

In this article, let’s understand it all.

Why Prebid Server?

Prebid Server offers publishers a powerful solution to scale demand and improve programmatic performance, addressing key challenges in modern advertising setups. Its ability to seamlessly integrate multiple SSPs (Supply-Side Platforms) without being limited by latency is a major advantage, enabling up to 40% latency improvements compared to client-side configurations.

In a client-side setup, the browser manages auctions and sends multiple requests to the ad server, increasing latency. A server-side setup, by contrast, requires only a single request, shifting the auction process to the server, where it’s faster and more efficient. For publishers aiming to enhance both scalability and performance, Prebid Server is an ideal choice.

Prebid Server also excels in monetizing AMP (Accelerated Mobile Pages), which rely on the RTC (Real-Time Config) framework. This framework imposes strict limitations on header bidding, such as restricting requests to five and enforcing short 1000ms timeouts. Prebid Server overcomes these constraints with unified auctions and its ability to send requests to as many demand partners as needed. Its server infrastructure is significantly more robust than a browser, ensuring fast auctions without timeouts, unlocking greater revenue potential for publishers monetizing AMP pages.

Recent enhancements to Prebid Server have further solidified its position as a go-to solution for publishers:

• Expanded Demand Opportunities
  The latest versions (v3.X) includes support for new adapters, such as Nativo, broadening access to demand partners.

• Enhanced GDPR Compliance
  Improved support for GDPR compliance ensures responsible user data handling, meeting global privacy standards.

• Better Synchronization
  Updates to user sync URLs enhance platform synchronization, resulting in smoother operations across ad ecosystems.

With these capabilities and updates, Prebid Server empowers publishers to overcome latency, scalability, and privacy challenges while maximizing revenue potential.

How does Prebid Server work?

Here’s an overview of how Prebid Server works for banner and video ads:

Banners

• The prebid server parses the request and holds the auction

• The response is sent back to the browser

• Prebid.js also passes ad server targeting variables to the page, the page forwards the variables to the ad server.

• When an ad wins, the ad server responds with the Prebid Universal Creative.

• The Prebid Universal Creative renders the display creative

Video

• Prebid.js is configured to run the header auctions on the server-side.

• When a page loads, Prebid Server parses the request and holds the auctions (not Prebid.js as it happens on client-side bidding). 

• VAST XML bid responses are then stored in Prebid Cache.

• Prebid Server sends the results and Cache ID to the Prebid.js on the page. 

• Prebid.js passes the bid information to the player and the player calls the ad server (GAM). 

• When a header bidding partner wins, the ad server sends the URL from which to retrieve the VAST XML — back to the video player.

• The player pulls the winning VAST from the Prebid Cache and displays it appropriately. 

Hosting Options: Self-Hosted vs. Partner-Supported

When implementing a Prebid Server, you have two primary options:

1. Self-Hosted Prebid Server
   You take full control of the server infrastructure, configuration, and maintenance.

2. Partner-Hosted Prebid Server
   You leverage a pre-built server solution from a monetization partner, simplifying the setup and management process.
   ‍

Consider the following table to weigh the pros and cons of each approach:

Is there any Privacy Compliance with Prebid Server?

Prebid Server is designed to comply with major privacy regulations:

• GDPR
  Reads TCF 2.0 and 2.2 signals to enforce necessary actions, managing user consent for data access, basic ads, and other purposes.

• CCPA
  Supports reading the US Privacy Consent String and works with AMP (Accelerated Mobile Pages) for cross-platform compliance.

• COPPA
  Detects COPPA flags and takes appropriate actions to safeguard children's privacy.

• Activity Control Infrastructure
  Allows publishers to override privacy-sensitive activities, providing a centralized system for managing compliance across diverse regulations.

Recent Prebid 9.X updates as well bring significant advancements in user privacy control and data management, empowering publishers to navigate the evolving privacy needs. Here's a breakdown of the key updates:

1. Simplified Consent Management:

• TCF Focus: Prebid's GDPR modules have been renamed to TCF (Transparency and Consent Framework) modules. This reflects their alignment with industry-wide standards rather than specific regulations. It clarifies the modules' purpose and functionality for all users.

• USP Streamlining: The USP (US Privacy) string is no longer included in consent metadata. The USP module itself is removed from the recommended build. This simplifies the consent process and ensures compliance with evolving privacy regulations.

• GPP 1.0 Retirement: Support for GPP (Global Privacy Platform) 1.0 has been removed from the GPP module. This aligns with updates to the privacy framework.
  
  

2. Enhanced Publisher Control:

• Publisher Purpose Consent: Modules like sharedid now rely on publisher purpose consent instead of vendor consent within the TCF object. This change gives publishers more direct control over user data management and consent.

Does the Prebid Server have any disadvantages?

Discrepancy

Because server-side header bidding involves multiple platforms communicating through a centralized server, discrepancies in impressions or revenue can be higher compared to simpler setups. A strong, well-optimized server infrastructure is essential to minimize these gaps.
With a managed Prebid Server like Mile, the infrastructure and data flows are already optimized for minimal discrepancy, so publishers don’t need to handle any of this internally.

Troubleshooting

Troubleshooting a Prebid Server setup can be more complex. This comes partly from the open-source nature of Prebid and partly from the fact that most issues occur server-side rather than in the browser. This can make the debugging process time-consuming without the right expertise.
Mile simplifies this by handling Prebid Server maintenance, monitoring, debugging, and updates for you, ensuring issues are resolved quickly without draining your internal resources.

Infrastructure Cost

Server-side auctions require dedicated infrastructure. Building, scaling, and maintaining your own Prebid Server can be costly if done in-house, especially when factoring in uptime guarantees, monitoring, security, and DevOps resources.
A managed Prebid Server like Mile removes this burden entirely, you get enterprise-level infrastructure without the overhead of running your own servers.

Reduced Bid Prices (Match Rates)

Server-side header bidding naturally has lower cookie match rates because syncing IDs is more complex outside the browser. Lower match rates mean buyers may have less data available, which can sometimes lead to more conservative bids.Mile’s Prebid Server improves this with enhanced ID modules, better bidder connectivity, and optimized match workflows to maintain stronger match rates and protect publisher CPMs.

What’s the Ideal Setup with Prebid Server?

To optimize Prebid Server for peak performance, strategically allocate demand partners, prioritize top performers on the client-side based on response time, bid rate, and win rate, while channeling slower-responding partners to the server-side. 

Expand the bidder pool by integrating non-Prebid demand sources like Amazon's UAM and Google's Open Bidding. Also, for AMP pages, leverage Prebid Server to maximize revenue while adhering to strict performance benchmarks. 

Consider a hybrid approach to balance latency and revenue to maintain top performers on the client-side while migrating others to the server-side. 

To further refine your setup, implement dynamic timeout adjustment and AI-powered floor pricing to optimize auctions and maximize ad revenue. Finally, leverage modular frameworks to integrate specific plugins or modules, unlocking advanced header bidding features for enhanced revenue and user experience.

Remember that optimization is an ongoing process. Regularly monitor performance metrics to identify areas for improvement. By continuously analyzing your setup, you can ensure that both ad revenue and user experience remain consistently exceptional.