For years, brands built their marketing on data that customers never really agreed to hand over. Third-party cookies followed people around the web, data brokers sold audience lists, and platforms inferred your interests from your behaviour. That model is quietly falling apart, and the replacement has a slightly awkward name: zero-party data.
If you have seen the term thrown around and never got a straight answer on what it actually means, this post is for you. We will define it plainly, show how it compares to the other types of data you have heard of, explain why it suddenly matters, and cover how to collect it without making customers feel like they are being interrogated.
What zero-party data actually means
The term was coined by the research firm Forrester. Their analyst Fatemeh Khatibloo defined it as data that "a customer intentionally and proactively shares with a brand." That word "proactively" is the whole point. Zero-party data is information someone hands you on purpose, knowing exactly what they are giving and why.
A few concrete examples:
- A shopper tells you their skin is dry and sensitive, so you recommend the right moisturiser.
- A new subscriber says they are a total beginner, so you send the beginner email track rather than the advanced one.
- Someone picks "gifts for someone else" over "treat for myself", so you change the entire tone of what you show them.
None of that is guessed or inferred. The customer stated it directly. That makes it the most accurate and most trustworthy data you can hold, because it came straight from the source.
How it differs from first, second and third-party data
The easiest way to understand zero-party data is to line it up against the three types most marketers already know.
Third-party data is collected by someone who has no direct relationship with the customer, then sold or licensed on. Think audience segments bought from a data broker. It is the least accurate, the least private, and the type currently under the most pressure from regulators and browsers.
Second-party data is simply someone else's first-party data, shared or sold through a partnership. It can be useful, but it is not yours and you did not collect it.
First-party data is information you gather from your own customers through their interactions with you: pages they visit, products they buy, emails they open. It is valuable and you own it, but a lot of it is still inferred. You are watching behaviour and drawing conclusions.
Zero-party data sits one step closer than even first-party. Rather than watching what someone does and guessing why, you ask them directly and they tell you. It is declared, not observed. That is the distinction worth remembering: first-party data is what you observe, zero-party data is what customers choose to declare.
Why zero-party data matters now
Two forces have pushed this from a niche idea to a mainstream priority.
The first is the collapse of the old tracking model. Privacy regulation has tightened, browsers have restricted cross-site tracking, and the reliability of inferred, third-party signals has fallen sharply. Marketers feel it: in the 2025 Braze Global Customer Engagement Review, 99% of surveyed marketing executives said their plans to use advanced personalisation had been affected by data privacy concerns. When the signals you used to rely on dry up, data that customers volunteer becomes far more valuable.
The second force is that personalisation expectations keep rising. McKinsey found that 71% of consumers now expect personalised interactions and 76% get frustrated when they do not receive them. You cannot personalise well without knowing who someone is and what they want, and the cleanest way to know that is to have them tell you.
Brands noticed. A Forrester Consulting study found that 90% of businesses were planning to capture zero-party data within the following year. This is no longer a fringe tactic.
The catch: people share, but only on their terms
Here is the part brands get wrong. Customers are genuinely willing to share, but only when the exchange feels fair and transparent. Accenture research found that 83% of consumers are happy to share their data to enable a personalised experience, but the willingness to share rises specifically when brands are transparent about how the data will be used.
So the goal is not to extract as much as possible. It is to make a clear, honest trade: you tell me something useful about yourself, and I give you something better in return, whether that is a sharper recommendation, more relevant content, or simply not being shown things that are irrelevant to you.
How to collect it without annoying customers
The fastest way to annoy someone is to demand personal information before you have given them any reason to trust you. A long form on a first visit, a pop-up asking for a phone number, an intrusive survey with no obvious payoff. Get these wrong and people either bounce or lie.
A few principles make the exchange feel fair:
- Give something back immediately. The value should be obvious and instant, not "we might email you a discount someday".
- Ask only what you will actually use. Every extra question lowers completion. If a data point will not change what you do, do not ask for it.
- Make it feel like a benefit, not a form. People happily answer questions when it leads somewhere useful for them.
- Be clear about the why. A single line explaining how their answer improves their experience noticeably increases how much people share.
This is exactly why the humble quiz has become one of the cleanest zero-party data collection methods around. A short, well-designed quiz flips the whole interaction. Instead of asking people to fill in a form for your benefit, you offer them a result they actually want - a recommendation, a personality type, a tailored suggestion - and the answers they give along the way are, by definition, zero-party data. They are declaring their preferences on purpose, in exchange for something valuable, and usually enjoying the process.
Done well, a few well-chosen questions can tell you more about someone's real motivations than months of watching their clicks. And because the customer volunteered it, you can act on it without the privacy risk that hangs over inferred data. If you want the practical mechanics, our guide on how to get more customers to complete your quiz covers completion rates in detail, and once you have the answers, how to use quiz data to write better ad copy shows what to do with them.
Zero-party data and personas
The real payoff comes when you stop treating individual answers as isolated data points and start turning them into a picture of who your audience actually is. Declared preferences map neatly onto psychographic segmentation - values, motivations and attitudes rather than just age and postcode. Stack enough of them together and you can build a genuine customer persona grounded in what customers told you, not what you assumed. That is the difference between a persona that sits in a slide deck and one that changes how you market.
The takeaway
Zero-party data is simply information customers choose to give you, knowing what they are sharing and why. It is more accurate than inferred data, more durable than third-party tracking, and it is becoming the foundation of privacy-first marketing. The brands that win will not be the ones that collect the most data. They will be the ones that make the exchange feel fair enough that customers want to share in the first place.
Try it with Profyl
Profyl helps brands collect zero-party data the way customers actually enjoy - through short, branded quizzes that turn honest answers into clear audience personas. No research agency, no guesswork, just your customers telling you who they are. See how it works at profyl.app.