How Buffer sold a product that didn't exist yet

Before writing a single line of code, Buffer's founder Joel Gascoigne built a two-page website. The first page pitched the idea — a tool to schedule social media posts — and had a "Plans & Pricing" button. Click it, and instead of a checkout you got a message: "You caught us before we're ready" plus an email box. Enough people clicked through the paid tiers that he knew the idea had real demand. Only then did he start building.

This is a smoke test (or fake-door test): you advertise a product as if it exists and measure whether people take a real action toward buying it. The point isn't to trick anyone — it's to replace the cheap, misleading signal of "would you use this?" with a costlier, more honest one: clicking buy, entering an email, or pulling out a card.

The deeper lesson is about willingness to pay versus stated interest. People are generous with compliments and stingy with money. A survey saying "90% love the idea" tells you little; a landing page where 40% click the $10 plan tells you a lot. The best validation asks for a small sacrifice — time, an email, ideally cash — because only sacrifice reveals genuine intent.