Advertising, Marketing & Identity Data
The ad-tech ecosystem that tracks you across the web
How Ad-Tech Data Brokers Work
Every time you load a webpage with ads, your data is broadcast to hundreds of companies in milliseconds through a process called real-time bidding (RTB). Your location, browsing history, device identifiers, and inferred interests are packaged into “bid requests” and sent to advertisers who compete to show you an ad. The Irish Council for Civil Liberties estimated that RTB exposes each American’s data 747 times per day, resulting in 294 billion bid request broadcasts daily in the U.S. alone.[1] These figures are described as low estimates because they exclude Facebook and Amazon RTB broadcasts.[1] RTB is a $117+ billion industry.[2] The companies listed below are the infrastructure that makes this possible.
Audience Data and Ad-Tech Platforms
Lotame
What they are: Publicis Groupe announced its acquisition of Lotame in March 2025, with the deal expected to close in Q2 2025.[3] Lotame operates one of the largest end-to-end data marketplaces in the world, spanning 109 countries with 100+ data sources and more than 1.6 billion addressable IDs.[3] Serves over 4,000 of the world’s leading brands and publishers.
How it works: Lotame aggregates audience data from publishers, apps, and third-party sources, then packages it into targetable segments — everything from “luxury car intenders” to “expecting parents” — that advertisers can buy to reach specific audiences at scale. The Publicis acquisition combines Lotame with Publicis’s existing 2.3 billion global profiles, which the companies claim will enable them to reach 91% of adult internet users with personalized messaging.[4]
The Trade Desk
What they are: Publicly traded (NASDAQ: TTD). One of the largest demand-side advertising platforms in the world. Processes vast amounts of advertising and audience data.
Why they matter: Developed Unified ID 2.0 (UID2) as a replacement for third-party cookies.[5] UID2 creates a persistent identifier from your email address (hashed and encrypted), allowing advertisers to track you across websites and devices even after browsers phase out cookies. The industry framing is “privacy-first” — but the outcome is the same: cross-site tracking tied to your identity. UID2 has been adopted as an open-source framework by numerous industry players, and is now managed by Prebid.org.
Eyeota
What they are: Acquired by Dun & Bradstreet in 2021.[6] Global audience data marketplace, originally Singapore-based. Connects audience data from publishers and data owners to advertisers across display, mobile, social, and video channels.
Bombora
What they are: Pioneer of B2B Intent data. Operates a co-op of thousands of publishers capturing buying signals from 17 billion monthly interactions.[7] When someone at a company researches a topic heavily, Bombora flags that company as “in-market” for related products — and sells that signal to sales teams.
Controversies: Bombora sued ZoomInfo in 2021, alleging that ZoomInfo used its free “Community Edition” tool to collect and sell B2B contact data without permission, in violation of CCPA. The companies reached a settlement in 2023.[8]
ShareThis
What they are: Collects data from social sharing buttons and widgets placed on hundreds of thousands of websites. Every time you see a “Share” button on a site, it may be collecting data about your visit and feeding it into ShareThis’s advertising data marketplace — whether you click it or not.[9] Privacy International profiled ShareThis as a “tracking as a service” company, noting its use of cookies and canvas fingerprinting to compile browsing histories into profiles across sites.[9]
Identity Resolution Companies
These companies specialize in connecting your different identities across devices, platforms, and the online/offline divide. The goal is simple: build a single profile that follows you everywhere.
LiveRamp
What they are: Operates the RampID identity graph (formerly IdentityLink) connecting online and offline identifiers. LiveRamp is the infrastructure backbone of cross-channel advertising — the plumbing that allows brands to match their customer lists to ad platforms, publishers, and data providers. Maintains what it calls the largest people-based identity graph in the world, with detailed information on an estimated 700 million consumers globally, including more than 250 million consumers in the United States.[10]
How it works: A retailer uploads their customer email list to LiveRamp. LiveRamp matches those emails to its identity graph and creates anonymized RampIDs that can be used to target those same people on Facebook, Google, The Trade Desk, and hundreds of other platforms. Your “offline” purchase at a store gets linked to your online browsing. LiveRamp also operates a Data Marketplace where it sells datasets that can target consumers based on sensitive attributes.[11]
Controversies: A class action for invasion of privacy was filed against LiveRamp in federal court in San Francisco, alleging that LiveRamp violated consumer privacy by making personal information available for sale through its RampID and Data Marketplace without consent.[12] A Cracked Labs research report documented LiveRamp’s role as “pervasive identity surveillance for marketing purposes.”[13]
FullContact
What they are: Identity resolution platform combining social media profiles, business directories, and public records into unified consumer profiles. Takes a single identifier — an email address, phone number, or physical address — and returns a comprehensive profile.
Tapad (Experian)
What they are: Cross-device identity graph matching consumers across computers, phones, tablets, and connected TVs. 91.2% accuracy per a 2014 Nielsen study.[14] Originally acquired by Norway’s Telenor Group for $360 million in 2016, then sold to Experian in November 2020,[15] giving it access to one of the largest consumer data sets in the world.
Drawbridge (LinkedIn/Microsoft)
What they are: Cross-device identity graph using probabilistic methods — meaning it infers that two devices belong to the same person based on behavioral patterns rather than deterministic matches. 97.3% accuracy per Nielsen.[14] Acquired by LinkedIn (Microsoft) in 2019.[16]
TowerData
What they are: Email intelligence company. Give them an email address and they return demographic data, purchase behavior, interests, and household information. Links email addresses to consumer profiles for marketing enrichment.
Stirista
What they are: Identity-based multichannel marketing data provider. Connects consumer identities across email, postal, mobile, social, and digital advertising channels.
B2B Data Brokers
These companies collect and sell professional contact information — your work email, direct phone number, job title, company, and more — to sales teams and recruiters. If you have ever received a cold email from someone who clearly bought your contact details, one of these companies is likely the source.
ZoomInfo
Scale: Approximately 321 million professional contacts across 104 million company records, processing 1.5+ billion data points daily.[17]
How they get it: ZoomInfo sources data from web scraping, public filings, user-contributed data (their free “Community Edition” requires users to share their email contacts in exchange for access), partnerships, and proprietary collection methods. If a colleague signed up for the free tier, your contact information may have been uploaded without your knowledge. ZoomInfo scans the email signatures of Community Edition users to harvest contacts.[8]
Enforcement and lawsuits: Settled a $29.55 million privacy class action (Ramos et al. v. ZoomInfo) over allegations that ZoomInfo violated California, Illinois, Indiana, and Nevada state privacy laws by using personal information to advertise its services.[18] Separately, Bombora sued ZoomInfo for allegedly gaining an unfair advantage by breaching CCPA through its Community Edition data scraping; the companies settled in 2023.[8] A securities fraud class action allowed to proceed in October 2025.[19]
Apollo.io
Scale: 275+ million contacts, 30+ million companies.[20] One of the fastest-growing B2B data platforms, popular with startups and sales teams.
Scandals: In July 2018, Apollo left a database containing more than 200 million contact records publicly exposed without password protection, one of the largest B2B data breaches ever reported.[21] LinkedIn took down Apollo.io’s business page in a crackdown on aggressive data scraping and browser extension use that violated LinkedIn’s Terms of Service.[22]
RocketReach
Scale: 700+ million professional profiles from 35 million companies.[23] Ranked #1 in Optery’s Top 50 Biggest Data Brokers by Google page indexing — nearly 5 million pages of professional profiles indexed and publicly searchable.[24]
Cognism
What they are: GDPR-compliant B2B data provider. Differentiates itself with phone-verified mobile numbers. Strong presence in EMEA markets.
Lusha
Scale: 150+ million business professionals. Israel-based. Offers a browser extension that reveals contact details when viewing LinkedIn profiles or company websites.
Clearbit (HubSpot)
What they are: Acquired by HubSpot in November 2023.[25] B2B data enrichment via API — feed in an email address or domain and get back company size, industry, revenue, technology stack, and employee details. Now integrated directly into HubSpot’s CRM platform as “Breeze Intelligence.”
Pipl
What they are: Digital identity resolution combining online and offline sources. Specializes in connecting fragmented identity data points into unified profiles for fraud prevention, investigations, and marketing.
Seamless.AI, SalesIntel, Demandbase
Additional B2B contact and intent data providers operating in the same space — each maintaining tens to hundreds of millions of professional profiles sourced from web scraping, public records, and data partnerships. Seamless.AI was also targeted in LinkedIn’s 2024 crackdown on data scrapers.[22]