Bidstream Data in Advertising: A Targeting Guide for 2026

Data is that new gold! Especially after Google announced the abolition of 3rd party-cookies in Chrome, it feels like the gold rush has started all over again. First-party data, third-party data, and sources that enable targeting...

Bidstream data now matters more because advertisers need targeting signals that do not depend only on third party cookies. If you already run campaigns through a demand-side platform, this data helps the bidder evaluate each impression before it places a bid.

According to EMARKETER, programmatic accounted for nearly 9 in 10 digital display ad dollars worldwide in 2025. That means bid request data is no longer a hidden technical layer. It shapes how advertisers buy, how publishers sell, and how both sides handle privacy pressure.

If you came here asking what is bidstream data, think of it as the technical profile of an ad opportunity. It tells the demand side what is available, where the impression may appear, which ad format is requested, and what contextual or identity signals may help evaluate the bid.

What is Bidstream Data?

In simple terms, bidstream data is the information that a supply-side (publisher) passes to the demand side (advertisers) to help them decide whether to bid on this piece of inventory.

In more detail, bidstream data is a piece of code containing encrypted details about the "offer" passed with the bid request from the supply-side platform (or perhaps an ad server) to ad exchanges, and eventually, demand-side platforms. Bidstream data is typically packaged as a JSON object and contains several categories of signals including contextual data, device information, location signals, ad specifications, and user identifiers.

Bidstream data does not contain PII (personally identifiable information), but it does contain information about:

• the inventory that is being offered: domain of the site, the domain of the extended page where the ad will be displayed, ad unit format and size;
• user location: IP address, geo, ZIP code;
• user device properties: type and model, screen size, etc.

In a cookieless environment, bidstream data enables contextual advertising by allowing advertisers to leverage real-time information about user behavior and preferences without relying on third-party cookies. In some cases, bidstream data may contain up to 50 attributes, including bits that are considered personal information, but predominantly, when we talk about bidstream data, we mean location.

Important note: DSPs receive information about all bids, including those that were not the winning bids.

How is Bidstream Data Collected in Real Time Bidding?

Step #1. Basically, any digital RTB auction is a user visiting the website/app.

Step #2. The publisher/SSP gets the user's information from their server. Sprinkle in their information about the ad spot and the bid floor, thus turning it into a bid request.

Step #3. This bid request is then sent by the SSP to an ad exchange (or several exchanges), where it receives multiple bids from the demand-side platform (DSP).

Step #4. All the DSPs (!) receive this information about the placement and the user, and the bid that best matches the bid request eventually wins.

So, when the system has made the perfect match and chosen the winning bid, it sends the bid's information, now including the creative, back to the SSP. And the SSP sends it back to the publishers, so the user can now see the ad (from the winning bid) in the designated place on the web page.

*champagne to all the participants*

Important note: While it may sound like a journey, it happens in milliseconds.

Why is Bidstream Data Valuable for Programmatic Advertising?

In reality, bidstream data is useful to all parties involved in the programmatic process, including ad buyers and sellers. It helps to marry the sell and buy-side in digital heaven. Bidstream helps transport all necessary and additional information from the publisher to the advertiser, helping everyone win with the best possible match.

Let's see how the collection and wise use of bidstream data can help all parties here.

Benefits of Bidstream Data for Publishers

As privacy regulations tighten, the use of first-party data is projected to increase by 40-70% among advertisers, indicating a shift towards privacy-safe identity models in the bidstream data landscape.

Higher monetization. Publishers can sell their inventory at the highest rate by providing information about the user and the ad spot. Initially, bidstream data was developed to help publishers achieve higher CPMs for their inventory.

Use of data. Publishers can put their location data to use: perhaps joining a Unified ID or selling it to a DMP. In our guide, you can read more about trends in 1st party data.

In addition, consider the scope of the growth. Six years ago, in 2020, US marketers were expected to spend $31.1 billion on location-specific advertising enabled by bidstream data, with projections to grow to $38.7 billion in 2021. In 2025, the number was $142.96 billion and is expected to reach $166 billion by the end of 2026.

Benefits of Bidstream Data for Advertisers

Advertisers can use bidstream data to fine-tune their ad targeting strategies by analyzing the device type and content being viewed by users in real-time.

Better segmentation of users. When advertisers use the white-label DSP, they can access all user data passed during the RTB auction.

Analytics. With this much user data on hand, advertisers can understand user behavior and how they perceive different campaigns based on various impersonal attributes, thereby cutting underperforming locations. Additionally, using hardware-based data security measures ensures that this sensitive user data remains protected against potential breaches, enhancing the privacy of the advertising efforts.

Besides, The Interactive Advertising Bureau's (IAB) OpenRTB standard has been updated to enhance security and transparency in the ad supply chain, which is expected to improve the effectiveness of bidstream data in future advertising strategies. Also, Privacy advocates have raised concerns regarding the aggregation of detailed location data and persistent identifiers in bidstream data.

Predictions and targeting. Given all the data (and it's a lot), advertisers can predict users' behavior for future campaigns and target precise, narrow audiences without any additional data or instruments.

Benefits of Bidstream Data for Users

Relevance. One of the top reasons why people switch on ad blockers is that the ads they see are irrelevant. So, upgrading the relevancy game is a significant advantage over the others. It seems like the phasing out of 3rd-party cookies will put a halt to it, but with the wise use of bidstream data, it doesn't have to.

Check in-depth insights delivered by experts in adtech. Especially, if you feel like you would like to learn more about possible players in the ad tech industry.

Drawbacks and Challenges of the Bidstream Data

Managing the sheer volume of bidstream data requires significant investment in in-house staff, machine learning tools, and high storage costs. Let’s take a closer look at all the aspects.

Challenges:

Bidstream data provides us with a ton of user data. However, to make use of you would need:

• an in-house team (for sure), who will extract this data from the DSP and analyze it;
• a machine learning tool that would sort through the data and break it down into digestible categories.
• significant data inaccuracies, privacy concerns, and high technical requirements are challenges associated with bidstream data management.

Drawbacks:

Bidstream data does not provide precise, parsed information like a DMP. However, it is like a separate investment given its price, and we are not 100% sure if it is always justified.

“Bidstream data is useful only when the team knows which signals matter for bidding, reporting, and privacy,” says an Epom specialist.

Obviously, if your ad budget is in the hundreds of thousands of dollars, it probably makes sense to invest in multiple tools. But we see no reason for that if you are using a white-label DSP solution that provides you with a perfectly working instrument that is also free.

Can Bidstream Data Replace DMP or Third Party Cookies?

The bidstream data cannot replace DMP or 3rd-party cookies. Otherwise, there would have been no drama surrounding Google Chrome over the last two years.

However, bidstream data can undoubtedly provide enough information to create highly targeted ad campaigns. Sure, given the information from the chapter above, it would require you to be a white-label DSP user and have a team of professionals who can use this data.

Here is when we recommend using a WL DSP:

• If your monthly advertising spend is $20 000 or more, a WL DSP is a sounder solution.
• Since 3rd-party cookies are going away anyway and the industry is creating all sorts of Unified IDs, publisher cohorts, etc., why not take advantage of a feature that has proven to work?

As for the DMP (Data Management Platform), we should understand that with bidstream data, there is obviously no management part.

Bidstream data provides you with a great amount of information that you should sort and manage yourself. There are no pre-set user segments ready to be targeted like in a DMP. However, having all the data on hand, you can parse it to your liking (needs).

Also, DMPs rely on 3rd-party cookies and therefore will not be as efficient when the "time to say goodbye" comes if they don't implement a solution based on 1st-party data.

Medium importance note: unlike a DMP, bidstream data is free.

Controversy Surrounding Bidstream Data: Privacy Standards and Regulations

Bidstream data broadcasts information to numerous companies, leading to increased scrutiny from regulatory bodies. With the ever-rising popularity of data, the question of data protection becomes more acute. GDPR (General Data Protection Regulation) in the EU, CCPA (California Consumer Privacy Act), and other institutions in the US are meant to protect us, regular users, from the spread and leakage of personal information.

The reason the odious 3rd-party cookies are crumbling is exactly that: There is too much personal user information circulating online, and not everyone uses it for good. The collection and repurposing of bidstream data often occurs without explicit user consent, leading to regulatory risks.

However, do these restrictions apply to bidstream data? Well, this is honestly a philosophical question. Some say yes, some say no, but if we were to put all the lyrics aside and look at the facts:

1. Bidstream data sits on the edge of the GDPR and CCPA visions of privacy, since location is kind of a personal identifier.
2. The most recent IAB RTB 3.0 protocol provided greater freedom and flexibility with bidstream data. Does it contradict its own user privacy policy? Maybe. However, at the moment, the industry will not allow the "killing" of RTB advertising for sure;
3. The abolition of 3rd-party cookies may strip bidstream data of some more personal identifiers, but there will be enough to stitch various user identity attributes into specific categories for tracking.

As privacy regulations evolve, the use of bidstream data is shifting towards contextual targeting, which relies on real-time data about the ad impression rather than user-level tracking, thus enhancing user privacy.

How Bidstream Data Works from the Tech Point?

As we have learned, all parties in the programmatic ecosystem benefit from bidstream data, but there is a category of advertisers that benefits more than others, white-label DSP users. They are the ones who get access to all the publishers’ user data.

Self-serve DSP also relies on bidstream data, but only to make bid requests. Its users have no access to the information or its further use for personal purposes.

If we consider DSP users, they receive an extensive file containing all bidstream data. This file can then be run through a machine learning tool that analyzes, parses, and segments users into categories.

This way, a separate advertiser gains full control over user data and can create as many unique targeting categories as one likes, and predict user behavior based on historical data from previous campaigns.

Based on Epom observations, teams get the most value from bidstream data when they connect it to campaign goals, not when they store every signal forever.

Key Takeaways from the Bidstream Data Collection

• Bidstream data is non-personal user data that is transferred from a publisher to an advertiser during the RTB auction.
• It exists to make the RTB possible and effective.
• It is a free tool once you use a white-label DSP.
• To make use of all the bidstream data, you need an in-house team and machine learning tools to help you manage, analyze, and parse the data (buy, Boy, is it worth it!);
• Bidstream data is not illegal under the Privacy Policy, as it does not contain personal identifiers.
• Bidstream data is a worthy alternative for the DMP, 3rd-party cookies (at its level);
• Bidstream data is here to stay even when 3rd-party cookies are long gone.

FAQs

• What is the meaning of bidstream?

  Bidstream means the flow of auction data passed during real-time bidding. The bidstream includes details about the user context, device, ad placement, and bidding conditions.

• What is bidstream data in advertising?

  Bidstream data is the set of signals sent through a bid request when an impression becomes available. Advertisers use those signals to decide whether to bid and how much that impression is worth.

• What is a programmatic bidstream?

  A programmatic bidstream is the data trail created during automated ad auctions. It helps DSPs evaluate impressions in real time and match campaigns with available inventory.

• How is bidstream data collected?

  Bidstream data is collected when a user loads a website or app with available ad space. The publisher side sends a bid request to ad exchanges and DSPs, and that request carries the auction signals.

• What is bidstream intent data?

  Bidstream intent data is auction-level information used to infer user interest or context. It may include page category, device type, location, time, and ad placement details, but it does not, by itself, prove purchase intent.

• Can bidstream data replace third party cookies?

  Bidstream data cannot fully replace third party cookies. It can support contextual targeting and auction-level analysis, but advertisers still need consented first-party data for stronger identity and retention strategies.

• Is bidstream data privacy-safe?

  Bidstream data can be privacy-safe when companies limit data collection, respect consent signals, remove unnecessary identifiers, and comply with privacy rules. The risk grows when auction data gets stored, resold, or reused without clear user consent.