Clue

Aida Tannen came to the idea for Clue during her late twenties, after a varied entrepreneurial journey that included a jewelry design company in London and a motorcycle touring business. While riding motorcycles through deserts and leading global tours, she developed a comfort with unknowns and an ability to learn quickly—skills that would prove essential for her next venture. The spark came when she realized no one had created a modern, data-driven solution for women to manage their reproductive health. She dug into patent databases expecting to find innovations, but discovered everything focused on hormonal interventions. Then it hit her: if women knew exactly where they were in their cycle, they could strategically use contraception like condoms on fertile days and avoid unnecessary hormonal birth control. With only 30% of women in Europe and America on hormonal birth control, Aida had identified a massive, underserved need.

Clue started with five co-founders who were "basically out of money the day we founded the company," according to Aida. They lived cheaply and went straight into fundraising mode. Their first capital came from angel investors in their network, beginning with a convertible note round that raised 50,000 euros initially. The angels grew in ticket size and sophistication, eventually accumulating about 1 million euros. A major milestone came when they landed a super angel who invested 1 million euros, giving them enough runway to approach institutional investors. When they pitched their Series A as a pre-revenue company, valuation negotiations were fluid—driven more by growth metrics and user trajectory than by traditional revenue multiples. Notably, their user base doubled between signing the term sheet and receiving the money in the bank, which Aida leveraged as evidence of momentum.

Clue's growth was organic and explosive. By the time of this interview, the app had nearly 3 million monthly active users (defined as users returning at least once per month) across 180+ countries. In a single month, they recorded 500,000 downloads, with December hitting even higher numbers. The app's appeal came from solving a real problem elegantly: women could easily log their period, mood, pain, sex drive, and other health markers, then get clear insights into their cycle. The simplicity and accuracy of the product drove strong word-of-mouth adoption, particularly in key markets like Germany, France, Mexico, and the US, where Clue became one of the top health and fitness apps.

Aida's strategic decision to prioritize growth over revenue proved effective with investors who shared her vision. She assembled a team of 24 people with a monthly burn rate around $200,000, betting that strong user metrics would enable them to raise a Series B within the next year. Rather than rushing to monetize, Clue planned to introduce revenue features that would enhance, not detract from, user experience—native features users would want to pay for rather than ads or friction. This patient, user-first approach worked: the app became genuinely popular, not just downloaded-and-deleted. Aida remained calm about the burn rate because she believed the team was building what would attract serious institutional capital.

With $10 million raised from Union Square Ventures and other top-tier investors, Clue had established itself as the world's fastest-growing period tracking and fertility app. The team was lean, efficient, and laser-focused on product and growth. Aida was balancing leadership of a high-growth startup while raising two young children (ages 1 and 5), embodying the resourcefulness that had always defined her. She hadn't finalized a monetization timeline but suggested it might happen within a year. The next inflection point would be the Series B, which she planned to pursue in the following year. For now, Clue was the rare high-growth SaaS company that had proven users would engage deeply with the product—a foundation that made eventual monetization feel inevitable rather than risky.