The same day Adobe's Fireworks discontinuation news broke, the company publicly and directly positioned Sketch as the replacement.

“Since the news leaked yesterday many people have been looking at Sketch and asking us whether we see ourselves as a Fireworks competitor/successor. The answer to that is a resounding YES”

Pieter later called it a watershed moment because it created a large pool of designers actively shopping for a replacement, and Sketch was the most visible option to them.

Pieter points to ongoing Designer News discussion threads as a visible sign of Sketch's rising interest within the design community, though he does not quantify the effect.

The company attributes sustained organic growth partly to an early decision to keep Sketch's file format open, which let outside developers build a large plugin ecosystem around the app; the community also organized its own meetups in cities worldwide.