One person.
No company behind him.

I'm an engineer, not a doctor. I want to be precise about what that means, because a lot of health content is vague about it on purpose.

What I actually have is build experience: I wrote Dew's on-device prediction engine, which meant reading the clinical guidance it had to follow — FIGO's 2018 menstrual cycle criteria and ACOG's normal-range definitions — closely enough to implement them correctly, and reading the large-scale cycle studies (npj Digital Medicine's analysis of 600,000+ cycles, the Apple Women's Health Study) closely enough to know where prediction breaks down and why.

So the explainers here are written from primary sources by someone who had to make an algorithm agree with them. That's the claim. It is not the same as clinical training, and I don't present it as such.

• Primary sources, cited inline. Medical claims link to the study, guideline, or regulator they come from — FIGO, ACOG, peer-reviewed journals, the FTC's own filings — not to another blog summarising them.
• Ranges, not false precision. Cycle science is statistical. Where the honest answer is “it varies, and here's the range,” that's what you get, even when a confident single number would read better.
• Competitors reviewed from documents. When I write that an app does something with your data, it's based on its published privacy policy, its App Store privacy label, or a regulatory action — quoted and dated, so you can check it. If a policy changes and I haven't caught up, the piece is wrong and I want to know.
• Corrections are visible. Updated articles carry a modified date. Substantive corrections are noted in the piece rather than quietly edited away.
• Nobody pays to appear here. No sponsored placements, no affiliate links, no paid reviews. Dew makes money from Dew — never from recommending anything else.

Dew estimates when your period is likely to arrive. It does not diagnose anything, it cannot confirm ovulation from a calendar alone, and it is not a contraceptive. It is general wellness software, not a medical device, and it isn't a substitute for a clinician who can actually examine you.

If something about your cycle worries you — sudden changes, severe pain, bleeding that isn't normal for you — please talk to a doctor. An app that tells you otherwise is selling you something.

Corrections, disagreements, and “you got this wrong” emails all go to the same place and I read them myself: [email protected].

Dew is on the App Store and Instagram.