What is a data broker — and why should you care?

The companies that know everything about you

You've heard of Google. You've heard of Meta. You've probably heard of Amazon. But there's a category of company you almost certainly haven't heard of — one that knows more about you than any of the above, has never asked for your consent, and profits directly from selling your personal information to anyone willing to pay.

These are data brokers. And there are thousands of them.

A data broker is a company whose primary business is collecting personal information about individuals from dozens or hundreds of sources, aggregating it into detailed profiles, and selling those profiles to third parties. Unlike social media companies that collect data as a byproduct of providing a service, data brokers exist specifically to collect and sell personal data. It is their product, their revenue model, and their entire reason for existing.

Where does the data come from?

Data brokers pull from an extraordinary range of sources, many of which you'd never expect:

• Public records: property ownership, court records, voter registration, marriage and divorce records, business filings, and more — all legally public in most jurisdictions.
• Purchase history: loyalty card programs, credit card transactions, and retail databases. When you use a supermarket loyalty card, that data often ends up with data brokers.
• Website behavior: tracking pixels, cookies, and browser fingerprints from millions of websites feed behavioral data into broker databases continuously.
• App data: hundreds of mobile apps sell location data and usage patterns to brokers. A weather app knowing your location 24/7 is worth a great deal to someone trying to understand your daily routine.
• Social media: public posts, likes, and connections are scraped and analyzed.
• Data purchases from other brokers: brokers buy from each other, creating an interconnected web where one data point can end up in hundreds of different profiles.

The major players

Company	Country	Specialty	Scale
Acxiom	US	Consumer profiles	2.5B people profiled
LiveRamp	US	Identity resolution	Links online/offline identity
Oracle Data Cloud	US	Ad targeting data	Billions of ad events/day
The Trade Desk	US	Ad buying + data	$1.8B revenue (2023)
Experian	IE	Credit + consumer data	1B+ people
Epsilon	US	Contact + marketing data	250M+ US consumers
Lotame	US	Audience segments	4B+ device profiles
Weborama	FR	European behavioral data	Major EU presence

What are data brokers used for?

The primary use case is targeted advertising. An advertiser wanting to reach 35–44-year-old women who have recently shown interest in home renovation and have an estimated household income above $80,000 can buy that exact audience segment from a data broker. This is the engine behind the $600 billion global digital advertising industry.

But advertising is not the only use:

• Insurance pricing: insurers use data broker profiles to assess risk and set premiums, sometimes using data points that would be illegal to ask about directly.
• Credit decisions: some lenders use "alternative data" from brokers to assess creditworthiness for people with limited credit history.
• Employment screening: background check companies pull from broker databases.
• Political campaigning: Cambridge Analytica was a data broker. Political campaigns routinely buy voter profiles.
• Law enforcement: US police departments have purchased location data from brokers to avoid needing warrants for surveillance.
• People search sites: sites like Spokeo and Whitepages are consumer-facing data brokers that let anyone look up detailed personal information about anyone else.

Are data brokers legal?

In most jurisdictions, yes — though the regulatory landscape is shifting. In the United States, there is no comprehensive federal law governing data brokers. A few states (California, Vermont, Texas) have introduced broker registration requirements, but enforcement is limited. In the EU, GDPR theoretically requires a legal basis for processing personal data, but enforcement against data brokers has been inconsistent and often slow.

The core problem is consent: most people whose data is collected and sold by brokers never consented to this use. The legal argument brokers make is that the data was collected lawfully at the source (e.g., a loyalty program with a privacy policy) and that they are simply processing it for "legitimate interests" — a GDPR basis that has been increasingly challenged by regulators.

How Data Mirror helps

Data Mirror monitors network requests in real time and identifies when your browser communicates with known data broker domains. When you visit a website that loads a pixel or script from LiveRamp, Lotame, The Trade Desk, or 21 other known broker platforms, Data Mirror flags it — showing you the broker's name, category, and their estimated contribution to your data's market value on that visit.

You can't stop data brokers from buying and selling your profile data that's already been collected. But you can see in real time which websites are feeding them new data — and make more informed choices about where you browse.