The strongest signal of product-market fit for Artemis came when their first design partners told them they wanted to buy the product before being asked. The product had become so integral to their daily operations that customers initiated the commercial discussion to ensure enterprise-level reliability.

Runway's founder knew he had found product-market fit not just from revenue, but when a major customer, AngelList, began running its business on the platform and became an evangelist. Deep adoption by a respected company is a far stronger signal of PMF than early sales traction alone.

The founder realized his product was essential when the customer Slack channel blew up with urgent feedback during their month-end close. This intense, demanding engagement signaled deep user reliance, unlike the 'empty platitudes' from users of a non-essential tool.

When a product addresses a significant need, early adopters will actively help you fix bugs and overcome hurdles. This intense engagement, despite product immaturity, is a powerful indicator of product-market fit. Users are willing to go "above and beyond" because the outcome is so valuable to them.

The clearest signal of product-market fit isn't just revenue growth; it's the shift from proactive, outbound sales to reactive, inbound interest. When potential customers start seeking you out, filling forms, and requesting quotes based on reputation and word-of-mouth, you've crossed the chasm from pushing a product to pulling a market.

Initially, customers often "round down," focusing on missing features. A key sign of product-market fit is when they start "rounding up"—their faces light up in demos, and they imagine the product's future potential, forgiving current limitations because they believe in the core value.

For enterprise startups, product-market fit isn't a gradual metrics climb. It's the moment a highly informed customer, after extensive market research, chooses your solution with unprecedented speed and for a significant contract value. This proves you are the undeniable choice.

You've achieved product-market fit when the market pulls you forward, characterized by growth driven entirely by organic referrals. If your customers are so passionate that they do the selling for you, you've moved beyond just a good idea.

The ultimate signal of product-market fit is when your go-to-market strategy simplifies to 'get a customer in a room with a prospect.' When customers become your most effective sales channel, you have found it, and your team can 'walk away'.