Missed the live webinar, watch it here!
Recap written by Thuy Ho
On 28 May 2025, Prebid.org hosted its annual Measurement Webinar, bringing together industry leaders to discuss the evolving challenges and innovative solutions shaping the future of advertising measurement. The session offered vital insights into why the shift to pre-bid measurement is necessary—and how it’s already driving results.
Speakers:
Alexey Stoletny (SVP, Engineering at HUMAN)
Geoff Stupay (SVP, Product at HUMAN)
Keith Candiotti (Founder & CEO at Optimera)
Key Takeaways from the Webinar
1. The Problem with Today’s Measurement
Today’s digital ad measurement still primarily happens after impressions are served. This delay creates critical inefficiencies:
- Valuable page-level data doesn’t always reach the bidstream, and when it does, it’s often unstructured or non-standardised.
- Advertisers struggle to assess inventory quality in real time, resulting in miscategorised inventory and lost bids.
- Publishers are penalised post-campaign through clawbacks, even when they follow advertiser guidance.
Worsening the situation, privacy-first changes by browsers and platforms are eroding signal quality. Tools like Apple’s Private Relay obscure IP addresses and device data, making bots and real users indistinguishable at the bid level.
2. Why Pre-Bid Measurement Matters
The solution? Measure before the bid. By enriching bid requests with standardised, secure, and verifiable data ahead of time, platforms can make real-time decisions that better serve advertisers while empowering publishers with more control and transparency.
3. The Work of the Prebid Measurement PMC
Since its 2023 inception, the Prebid Measurement PMC has made significant progress:
- HUMAN released the first real-time data module in early 2024, allowing for IVT filtering without adding latency.
- Partners like Optimera and Mobian have since contributed additional RTD modules, increasing adoption across the ecosystem.
- Experiments involving multiple publishers, a DSP, and an SSP have shown that 97% of bid requests can be successfully enriched, boosting signal accuracy without performance trade-offs.
4. Challenges from the Privacy Landscape
Despite the success of RTD modules, the work isn’t done. The measurement ecosystem faces increasing pressure from:
- Privacy constraints, which reduce the utility of traditional signals
- A lack of standardised frameworks across platforms
- The need for better collaboration between publishers, SSPs, DSPs, and measurement vendors
- To address this, the PMC is focusing on:
- Expanding the types of data signals passed with the bid
- Refining a scalable, marketplace-ready framework
- Increasing standardisation across partners
5. Q&A
Q: For SSPs and DSPs, does the use of data require a contract with HUMAN?
A: SSPs and DSPs that already have an active contract with HUMAN can use the system without any extra agreements. These platforms send bid request data, including publisher-provided signals, to HUMAN for real-time decisioning. They receive both real-time and offline reports. For publishers, providing these signals is free—HUMAN is not monetising the signal collection. The goal is to improve IVT (invalid traffic) detection in a privacy-safe way, without re-identifying users, by relying on the information already present in the bid request at the time it is made. This process does not add latency or compromise privacy.
Q: Who decrypts the enriched signal, SSP or DSP, and how is the decoder implemented?
A: SSPs and DSPs send encrypted signals along with bid request fields to HUMAN as part of a standard integration. Only HUMAN can decrypt and interpret these signals, which is crucial for security. If signals were sent in plain text, they could be easily spoofed, and platforms wouldn’t trust them. To prevent this, the signals must be encrypted, tamper-proof, and time-restricted. While HUMAN has its own method, other vendors participating in the PMC can build similar solutions, but they must also ensure their signals are securely encrypted and added to bid requests without causing delays.
Q: It sounds like the data being provided to platforms is being encrypted to protect its integrity. That’s explicitly not transparent. Has there been any consideration of providing signed data instead, which both assures integrity and supports transparency?
A: Each member of the task force or Prebid community building a pre-bid measurement solution can design it based on their own threat models and security needs. While HUMAN has its specific approach—combining encryption, signing, and obfuscation—others are free to implement their own methods as long as they ensure signal integrity and privacy. The framework is open, and any vendor can participate, provided they follow agreed standards. HUMAN and Optimera were the first to build into this framework, doing the early work to validate its value. Now that the approach has proven effective, the aim is to bring in more partners to build and adapt it for broader use.
Q: What exactly is the signal being collected, and what am I adding to my page to enable this signal collection?
A: Publishers already collect a wide range of signals for post-bid measurement (e.g. for IVT, brand safety, and verification). The goal of this initiative isn’t to collect more data, but to shift some of that signal collection to the pre-bid stage, so it can be used for real-time decision-making. This involves capturing a smaller, instantly available subset of signals without adding latency. It complements—rather than replaces—post-bid measurement and allows publishers to make smarter decisions earlier in the process.
Q: As a publisher, now that the HUMAN RTD module is implemented, is there a way to access the HUMAN signal in real time and use it to take action, such as blocking ads when invalid traffic is detected?
A: Currently, the HUMAN RTD module collects signals and passes them upstream to DSPs and SSPs for real-time decision-making, primarily to filter out invalid traffic (IVT). This benefits publishers indirectly by reducing post-campaign clawbacks and improving campaign quality. While publishers don’t yet have direct access to the signal data or tools to act on it themselves (e.g. blocking ads), HUMAN is open to developing publisher-facing transparency and reporting in the future. Participation in the task force may provide early access to aggregate insights.
Long-term, there’s interest in enabling publishers to use these signals within their ad servers (like GAM) to optimise direct and programmatic campaigns. This isn’t the current focus, as the priority is validating the system’s value in the open exchange. However, as adoption grows, extending signal use to broader publisher use cases is a likely progression.
Q: Is the HUMAN Security RTD available in a direct SSP-to-server integration mode, or does it require a purely client-side Prebid setup?
A: Currently, the HUMAN RTD module is available only as a JavaScript client-side integration. However, there is growing interest in expanding it to server-side and mobile SDK implementations, and those areas are part of future development plans. A server-side module does not yet exist, but contributions to Prebid for that capability are being considered.
6. The Road Ahead
Prebid.org and its partners are focused on:
- Expanding collaboration with SSPs and DSPs
- Refining frameworks for scalable implementation
- Standardising data collection to support real-time, pre-bid decisioning
Get Involved
The Measurement PMC invites publishers, platforms, and developers to participate by joining discussions, sharing feedback, and helping shape open standards on GitHub.