How this growth loop worked
A user recorded a screen video, and Loom turned it into a hosted page at a shareable URL. The creator dropped that link into an email, a Slack message, or a doc. Recipients opened it in a browser and watched, no account needed. Some wanted the same fast way to reply, so they signed up, recorded, and produced links of their own. Each finished video became a new entry point to the product.
The distribution channel was the product's own output. Every shared video carried a small pitch for Loom to a viewer who hadn't seen it, at no extra cost to produce. The K-factor here, near 0.30, doesn't sustain itself; on its own that loop decays toward zero. It still paid off: each signup pulled in a fraction more users for free, an amplifier that lowered blended acquisition cost, not a perpetual engine.
The lesson: ask whether your product's normal output can double as its distribution. Loom didn't bolt a referral program onto the side; the shareable artifact was the core action people already performed. Find a step users take anyway that puts your product in front of someone new, then strip friction at that entry point. Watching needed no login. A loop below 1 won't replace acquisition, but it makes every other channel cheaper.