Founders love building. That's the problem. The instinct to start coding skips the one step that kills most startups: checking whether anyone actually wants the thing.
The fatal-assumption test
Every idea rests on assumptions. Usually one of them is fatal and unchecked: "people will pay monthly for this," "they'll switch from the tool they already use," "acquisition will be cheap." Your job is to find that assumption before you spend three months building.
Get every angle, fast
Before you talk to a single customer, pressure-test the idea against the perspectives that matter:
- A founder finds the wedge: the magic moment that makes it spread.
- An investor asks how big it can get and why it retains.
- A skeptic names the assumption most likely to be fatal.
- A target customer answers the only question that counts: "would I actually pay?"
Debatly's startup idea validator runs this panel for you and ends with a go/no-go verdict plus the one assumption to validate first.
Then validate with real people
AI validation is the cheap first filter: it sharpens the idea and tells you what to test. The next step is always real customers: 10-20 conversations, a concierge test, a fake-door landing page. If you want help thinking through the go-to-market, run a business advisor debate.
Build second. Validate first.
“How to Validate a Startup Idea Before You Write Any Code”