Marketing platforms, like Meta, Google Ads, and others, offer powerful tools to help you understand which ads drive results. But to unlock their full potential, they often ask for something in return: user data, such as email addresses or physical addresses.
Should you share this data? What are the risks and benefits?
Let’s break it down in simple terms, focusing on data privacy, security, and how this practice impacts your marketing efforts.
Why do platforms want your users’ data?
Problem with Cookie-Based Tracking
When you run ads, you want to know which campaigns lead to sales. Traditional tracking relies on cookies—small files stored in a user’s browser. However, cookies have limitations:
- Short lifespan: On Safari (especially iPhones), cookies may only last about 7 days due to Apple’s privacy policies.
- Device/browser dependency: If a user switches devices or clears cookies, tracking breaks.
- Ad blockers: Many users block tracking scripts, making it harder to attribute conversions.
When these conditions fail, platforms lose visibility into which ads drove conversions. That’s where user data comes in.
How User Data Helps
By sending hashed (encrypted) user data, like email addresses or phone numbers, alongside conversion events, platforms can:
- Match data to user profiles: They check if the user has interacted with your ads before.
- Use statistical models: Platforms combine exact matches with AI to estimate which campaigns likely influenced the conversion.
- Fill in the gaps: Even if cookies fail, user data helps platforms attribute conversions more accurately.
Note: This isn’t perfect. Models are biased toward the platform’s own ads, and you should treat results as estimates.
How sending user data benefits your marketing efforts
In short…
- You get better campaign insights – you can see which campaigns perform better or worse within a platform, even if tracking isn’t perfect.
- It’s a work-around ad blockers – user data helps attribute conversions even when cookies are not available
- You avoid guesswork – you can use the data to optimize budgets, even if it’s not 100% precise.
What you need to take care of
If you’ve decided to send user data to marketing platforms, you need to take care of two things…
1. Privacy regulations
Regulations like GDPR (Europe) and CCPA (California) require you to inform users about data collection and obtain their consent before you send any data to any platform.
This may seem simple to do, but many policies do not include this information.
Fortunately tracking and consent management solutions help you with it. Our own WP Full Picture even goes one step further and tells you what information you need to include in your privacy policy, depending on the settings of your tracking tools (in the GDPR setup helper).
2. Data security
Send user data only when they are logged in to your website. The data cannot remain on their devices in any form – not in cookies, not in browser and local storage. And, what is often overlooked, make sure the data is not used in any URL, for example:
https://example.com/contact/?confirm=true&user-id=111&city=aaa&address=bbbYou can sometimes see URLs like these when a user sends a form and the page refreshes. These URLs will be picked up by all tracking tools on your site and be saved in their databases.
So, should you share user data?
Yes, but carefully and with consideration to data privacy, user consents and security.
