Third-party data isn’t deadEstimated reading time: 8 minutes
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Third-party data isn’t dead

By: Gillian MacPherson | September 8, 2026
Marketer evaluating third-party data sources and providers for campaign targeting

Is third-party data dead? Not even close.

Third-party data is information you buy from an outside source—not the company that originally collected it—to enrich what you already know about your customers with demographics, interests, purchases and more.

Despite the "death of third-party data" headlines, spend on quality third-party data keeps climbing because first-party data (https://www.epsilon.com/us/insights/blog/maximize-first-party-data) alone can't paint a complete picture of a customer.

Think about it: Even the biggest brands in the world might only have visitors coming every few weeks for a purchase (and that might be generous). No brand has enough information on any single person to really understand their current and potential needs on their own.

The catch is quality, since not all third-party data sources are created equal. Here's what third-party data actually is, where it comes from and five things to look for when choosing a provider.

What is third-party data?

Third-party data is data you buy from trusted external sources that aren't the original data collectors. It can come from a wide variety of digital and offline sources and is then aggregated, segmented and sold to marketers for their own advertising campaigns.

When you buy third-party data, you can buy the raw data to enrich your customer understanding or audience segments to activate across channels to reach the exact consumers you want your marketing campaigns to connect with.

Need a refresher on how third-party data differs from other data types? Our guide shares an overview of first-, second-, third- and zero-party data (https://www.epsilon.com/us/insights/blog/what-is-first-second-third-and-zero-party-data) to give you a complete picture.

Third-party data examples

Common examples of third-party data include:

  • Demographics
  • Financial data, such as income or net worth
  • Purchase information
  • Categorical interests
  • Online behaviors
  • Propensities and attitudes

Where third-party data comes from

Third-party data comes from a variety of sources, including offline, digital, panel and transactional sources.

Third-party data source types Definition
Offline data sources Offline data sources include public records, information from credit bureaus and survey results compiled by external aggregators or data brokers without a direct relationship to the consumer. 
Digital data sources Digital data sources include data brokers, online publishers and public records. These entities collect, aggregate and license audience information from multiple external touch points. 
Panel data sourcesPanel data sources give us consumer insights over time to help us understand trends, opinions and behaviors. External panel data sources might include consumer purchase panels, media viewership panels and specialized professional panels. 
Transactional data sourcesTransactional data sources are compiled from credit bureau networks, payment processors and retail scanner data cooperatives and can give us valuable insight into consumer spending, economic sentiment and more. 

Why third-party data is important

For years, there was a focus on reach in programmatic, which impacted quality. There was also limited scrutiny on data providers in terms of sourcing, the accuracy of data as well as the transparency into what was really being presented.

Thankfully, as marketers have become more sophisticated and with a shifting consumer and privacy landscape, this is changing. My hope is that this will clean up the industry and shine a light on data quality.

Third-party data should not be thought of in one sweeping statement—as with anything, there are valid and reliable sources that add to the overall picture of a consumer that first-party data alone cannot deliver, plus the ability of the provider to accurately aggregate those signals around specific individuals or households. A broader profile of consumers, including their interests, demographics, household composition and purchases, are very useful to help understand each person and improve personalization.

I’ve seen recent articles touting that first-party data can deliver it all, and any other sources are inferior and inaccurate. I have yet to come across a 100% accurate picture of a consumer from a single data source and have even seen inaccuracies from first-party data as they represent only a particular view of a consumer or are based on behavioral inferences from browsing behavior.

For example, Facebook thinks I have a toddler because I liked a friend’s picture, yet my kids are in their late teens. Additionally, they’re unaware that my brother has a dog since he purchases dog food at his vet, not a grocery or mass merchandise store. There are often inaccuracies, and marketers need to be aware of the degree of the flaws and how they impact both performance and the consumer experience with your brand.

So what’s a marketer to do? Educate yourself and ask lots of questions to ensure you know what you are getting, so you can be realistic about how it fits in with your plans and how different data sources can complement each other.

How to choose a third-party data provider

1. Think about what data you need and will use

Data is important to drive targeting to eliminate waste and also make the content more personal to each consumer. Distinguish between these two as they serve different purposes and may result in selecting different data sets. Targeting is about reaching the right person based on where they are in their consideration set along with a brand’s objective and awareness versus conversion.

This is a balance of scale versus accuracy. Anything too big can be meaningless, but anything too targeted can limit the impact and reduce efficiency.

Data for personalization makes the interaction with a consumer more meaningful and impactful—consistently providing what consumers say they want and expect. But a brand needs to be willing to vary both the creative and messaging for this to work to ensure this can be executed. It can be as simple as showing a dog image versus a cat image for pet owners (which I have seen show lift) or a family image versus a single male, and yet so few brands do it well or even at all.

2. Ask questions of every data provider to fully understand what is being provided

Take the time to review all data providers you’re working with and make sure to ask the right questions when evaluating each partner. And remember, no data set is perfect.

For example, transactional data is precise in terms of knowing what the consumer bought with a retailer, but understanding how much these transactions represent of the consumer’s total spend and how the data is managed is important. During your assessment, make sure to review:

  • How the data is linked to consumers? Do they use a cookie, IP address or device? And is it at the individual or household level?
  • Know the data derivation. Is it declared, derived, inferred, modeled or observed?
  • How often is the data refreshed?
  • For transactional data from retailers, it’s important to understand:
    • How are transactions captured and linked to an individual or household?
    • How many transactions can the retailer capture of total spend in their stores or a given consumer? Is it based on tender (plastic versus cash) or a loyalty card?
    • How many cardholders spend the majority of their possible spend with that retailer?
    • How much does that retailer represent of your brand’s sales? If it is grocery, how much else is purchased in mass, club, specialty, convenience or club?
    • Are multiple loyalty cards per person or household co-mingled or distinct?

3. Think quality over quantity

Did you know that over 25% of organizations estimate they lose more than 5 million USD annually due to poor data quality, with 7% reporting losses of 25 million USD or more? It’s true. Oftentimes marketers do not have the resources (or the time) to do a full data quality assessment to determine if their data is of quality.

In our data buyer's guide, we outline 10 key assessment criteria to consider when evaluating data quality and how AI fits into the picture. Remember, not all third-party data is created equally. Advertisers and agencies must be careful to validate the accuracy and validity of the partners they work with versus assuming all are either ‘bad or good’.

4. Make sure data is transparent

Understanding how data audiences are built is essential and making sure everything stated in the document/label is true is important for data success.

With recent initiatives like the IAB Data Label, the ecosystem is working to create transparency to eliminate poor data providers and hold all data providers accountable.

Check that your data provider is certified or in the process of certification to ensure what you think you are buying is actually what you are getting.

5. Ensure data is compliant

It’s important for data providers to share how they comply with current legislation in addition to how they’re preparing for new legislation. Make sure to continuously review privacy policies and opt-out language. At Epsilon, we protect and respect data, and we’re always thinking privacy. In our role as a trusted partner to clients, Epsilon remains committed to having a leadership role in shaping the changing privacy landscape.

Data is powerful. It’s the brains behind our marketing success. It’s critical to understanding consumers, reaching new buyers and to better communicate with existing customers. There is no silver bullet for the perfect data set, even first-party data.

This data is valuable when it’s of high quality, and multiple partners will always be necessary for full coverage of consumers and useful insights about them that are not skewed. Take the time to understand every partner you work with, and only work with those that are honest about their strengths, weaknesses and gaps.

Now that you better understand third-party data, learn more about how Epsilon can help.

This post was originally published on February 25, 2020, and has since been updated.

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