PERIOD. in De Ondernemer: from 0 to 50,000 users in 5 months

On 28 July 2026, Dutch business title De Ondernemer published an interview with our founders Lisa Volkers (30) and Diederick Trampe (28), headlined: "Cycle app Period. grew from 0 to 50,000 users in 5 months: 'We will never sell our data'".

The piece, written by Emma Kraanen, tells how PERIOD. grew out of a kitchen in Amsterdam into an app now used in more than 100 countries, and why privacy isn't a marketing feature for us, but the entire reason the product exists.

From frustration to app

Lisa, former editor-in-chief of Dutch magazine LINDA.meiden, explains where the idea came from: "Out of frustration. I was 29 and knew nothing about my cycle. The luteal phase? I had no idea what that meant." She found the existing cycle apps too pink, too full of paywalls, and then discovered how they handle privacy.

Diederick, who runs record label OBSCUUR, took the idea seriously straight away: "I was already building digital marketing tools for my label. I had the skills, so I offered to build the app." Three months of non-stop building later, the foundation was there. PERIOD. launched in March 2026.

50,000 users in over 100 countries

"We're at 50,000 in more than 100 countries now", Diederick says in the article. The couple funded development with tens of thousands of euros of their own savings, ship all updates themselves, and run no paid advertising (yet).

PERIOD. stays free at its core. On top of that there's PERIOD. plus at €3.99 a month, "an Amsterdam coffee", which lets you customise your layout, export PDF reports for your doctor, and chat with the AI assistant.

Privacy as the foundation

"We operate fully under the European General Data Protection Regulation (GDPR) and invest structurally in privacy and security: EU hosting, legal advice. That's the more expensive route, but it's the entire reason Period. exists", Lisa says. Diederick adds: "We ask users for as little data as possible. And we will never, ever sell our data."

The details are in our privacy statement and in Privacy at PERIOD. vs. other cycle apps.

Cycle knowledge at work

A big part of the interview is about how little most people know about the cycle. Lisa: "Which phases are there and what do they do to women? That knowledge is missing at home and at school." Employers, she argues, are equally unaware: "Because there's a taboo around menstruation and cycle-related symptoms, women often lie and say they're sick."

That's exactly why we built PERIOD. at work: PERIOD. plus as an employee benefit, fully anonymous to the employer. Lisa: "I think it sends a positive signal to women when an employer shows they're cycle-aware."

What's next

In the article Diederick mentions the new partner feature: with a code, your partner can follow along in the app. And he's clear about the ambition: "The idea is that Period. hits 100,000 users in September. But there's a good chance we'll get there sooner!"

Read the piece

The full interview (in Dutch) is on deondernemer.nl. More press coverage is on our media page.

Want to try it? Download PERIOD. on the App Store or Play Store.