Privacy Review: Clue

Yes, though Clue’s privacy tradeoffs look different from many other apps in this category.

Compared to other apps in this space, Clue is unusually upfront about how it wants to use your data. The app still asks for the usual stuff during setup, like whether you want to share your data for Clue’s analytics or advertising efforts, but this is the first time we’ve ever seen an app ask whether you also want to share that information to contribute to women’s health research.

Importantly, those settings remain accessible after signup: you can revisit and change them later instead of being locked into whatever you tapped during onboarding. That kind of ongoing control is rare. Most apps treat consent as a one-time checkbox, something you agree to at setup and never think about again, but Clue lets you revisit it again and again.

Clue’s privacy model isn’t built around collecting less. The app still asks its users to log a deeply personal portrait of their health: moods, symptoms, and what your reproductive goals are. The whole point of using an app like Clue is its forecasts and predictions, and those only work if you give it enough to go on.

During normal app use, we didn’t see any of the sensitive—stuff your symptoms, your cycle, your reproductive-health details—being shared outside the app. It wasn’t reaching any of the third parties we saw integrated into Clue.

Timestamps tied to specific in-app behavior: When we opened Clue, visited certain pages, or tracked new symptoms, we were routed through Clue’s internal analytics infrastructure, largely built on Snowplow. Logged symptoms were no exception. When we tracked a period as “very heavy,” for example, Clue's analytics recorded that, the timestamp, and the value we'd logged the time before.

But that might be the least interesting part of what Clue collects about you. Cycle dates aside, the app encourages users to log just about everything their bodies might be going through: cramps, bloating, spotting, headaches, skin changes, and cravings for certain foods.

Clue also treats other parts of your everyday life as potentially relevant: sleep schedules, stress levels, social battery, a user's smoking or drinking habits, and whether they traveled, went on a date, or had a doctor’s appointment on any given day.

Again, we didn’t see Clue broadly sharing any of this data with third-party partners when we used the app. That means we can’t really say Clue collects less of your data: it’s just deliberate about what it’s using it for.

In a category that’s repeatedly run into privacy controversies, Clue has managed to maintain a better reputation than most.

One investigation from Privacy International also found Clue's data practices comparatively restrained next to some competitors more deeply tied to advertising infrastructure. That posture has held steady on paper, too: according to snapshots archived by Berkman Klein's Transparency Hub, Clue's Supplemental Notice for U.S. users and its Consumer Health Data Policy remain word-for-word identical to versions captured nearly a year earlier.

The company’s European data practices have also been a major part of that steady reputation, with Clue repeatedly emphasizing that user data is stored under stricter EU privacy laws rather than in the United States.

That said, Clue hasn’t completely escaped the weirdness of the modern data economy. A 2022 Motherboard investigation found that data broker Narrative had previously sold datasets identifying devices with period-tracking apps installed—including Clue.

Clue did not respond to a request for comment.

Our new round of testing found that the same basic issue still exists: outside services might not see someone’s actual cycle logs, but some still receive enough information to tell when a device is using Clue.

If your main concern is whether the usual cast of data-brokering weirdos is learning the details of your cycle, Clue’s default settings go a long way. If your concern is whether Clue itself is building a detailed, long-term picture of your body and habits, that’s more or less the tradeoff behind using the app at all.

Clue is clearly deliberate in its privacy setup. When we saw the app sending data to Braze—a third-party platform that handles notifications and in-app prompts—we also saw Clue explicitly block a range of more sensitive details we’d logged (about birth control use and fertility tracking) from being piped through that interaction.

Clue also separates out data-sharing settings for research, analytics, and personalization instead of rolling everything into one giant “agree” button. That’s a deliberate design choice that implicitly acknowledges what most other apps don’t: that people care about the context of data sharing, not just whether it happens in the first place.

Clue also lets you revisit those choices long after you make an account, meaning you’re free to change your mind about your data anytime instead of being stuck with whatever options you first tapped on.

The tradeoff worth considering with Clue isn’t about advertising, but accumulation. In our testing, the app generated a detailed long-term record of health logs, app activity, and behavioral history, all tied to persistent identifiers.

Clue’s obligations under European privacy law place real limits on Clue’s ability to access or share your data, but they don’t make your data any less sensitive. Setting aside advertisers and data brokers for a second, there are still real risks that come with creating so many reproductive profiles on so many people, from breaches and legal requests to future misuse or exposure.

Finally, while Clue gives users more controls than many competitors, it still asks users to make sense of a pretty complicated data ecosystem. Most people aren’t realistically going to untangle the privacy tradeoffs tied to analytics, research participation, and app optimization. Even if they did, Clue would still know an enormous amount about them.

A few settings and habits can go a long way:

• Only track what actually feels useful to you. Clue encourages users to log an enormous range of information, from symptoms and mood changes to social behavior and lifestyle habits. You do not need to fill out every category for the app to function well. The less intimate detail you log over time, the smaller and less revealing your long-term record becomes.
  
• Revisit Clue’s privacy settings regularly. Clue separates out settings for different kinds of data use. It’s worth revisiting those settings occasionally, especially after major app updates or changes in how you use the app.
  
• Think carefully before linking outside accounts. Signing in with Google or connecting other services may be convenient, but it also makes it easier for outside companies to associate your identity with using a reproductive-health app in the first place. Using a dedicated email instead of a social sign-in can help keep that activity a bit more compartmentalized.
  
• Keep the tradeoffs in mind. Clue clearly feels more privacy-conscious than many period trackers we tested. But the app still fundamentally works by maintaining a highly detailed long-term health record, and no privacy setting fully changes that.

With some apps, the concern feels obvious: too many trackers, too many advertisers, too much sensitive information flowing everywhere at once. Clue comes closer than most in getting this right, but it also raises a different kind of privacy question, and one we don’t always ask: how much should any one company know about your body?

Clue is proof that apps in this category can make more thoughtful choices. It's also a reminder that thoughtful choices only go so far in protecting your privacy. The data you give it is still data: detailed, personal, and held by one company for as long as you keep using it. That's not a reason to avoid Clue, but it is worth knowing what you're signing up for.