We went from 0 to 2,200 paying customers in under a year by following @ycombinator's 15 rules:

1/ Do things that don't scale. Get your first 10 customers by hand.

2/ Launch now, not when it's "ready". A mediocre product in front of real users teaches you more in a week than 6… pic.twitter.com/Zot0PRw3OE

— Pierre-Eliott Lallemant (@pierreeliottlal) June 11, 2026

Y Combinator's 15 rules:

1/ Do things that don't scale. Get your first 10 customers by hand.

2/ Launch now, not when it's "ready". A mediocre product in front of real users teaches you more in a week than 6 months of polishing in the dark.

3/ Charge from day one. If nobody will pay, you don't have a startup, you have a hobby.

4/ Talk to users every single day. The roadmap you need is sitting in your customers' heads, and they'll hand it to you for free

5/ Always hunt the 90/10 solution. For almost any feature there's a way to capture 90% of the value with 10% of the effort.

6/ There are only two real jobs: write code and talk to users. Everything else (conferences, press, VC coffees, corp dev calls) is fake work.

7/ You pick your customers as much as they pick you. 10 users who love you beat 1,000 who kind of like you.

8/ Growth is an output, not a strategy. Grow before product market fit and all you're buying is churn.

9/ Do less, really well. Pick one or two metrics and judge every task against them.

10/ Know if you're default alive. Paul Graham's question: on current growth and current burn, do you reach profitability before the money runs out?

11/ Don't hire until it hurts. Headcount is not progress, it's burn. Every great startup was embarrassingly small for embarrassingly long.

12/ Momentum is the only real moat in year one. Ship something every week, even something tiny.

13/ Every great startup is badly broken at some point. The game isn't avoiding fires, it's how fast you put them out. Again. And again.

14/ Ignore your competitors. Startups die of suicide, not murder. In year one, the only company that can kill yours is your own.

15/ Startups rarely die from running out of money. They die because the founders fall out. Brutal honesty with your cofounder is the cheapest insurance you'll ever buy.