# Growth Loops: The Fuller Playbook

Phase 6.6 in SKILL.md is the beginner-light version: the reframe, the three buildable loop shapes, the three-question diagnostic, and the honest "not every app has one." This file is the detail behind it, the famous examples worth recognizing, the full taxonomy of loop types, how to sketch your loop's math, and the four ways to make a loop spin faster. Pull it in when the user wants to go deeper, or when their app clearly has a real loop worth designing with care. None of it needs a growth team.

It's translated from Brian Balfour and Reforge's work on growth loops, with Casey Winters and Kevin Kwok's loop taxonomy, kept in plain language for someone who's never shipped a product.

## Why a loop beats a funnel

The old way of thinking about growth is a **funnel**: a big crowd at the top (everyone who hears about you), narrowing step by step down to a few customers at the bottom. The problem is that a funnel is a one-way trip. Everyone who comes out the bottom is spent, and to get more customers you have to keep pouring more people in the top, which usually means spending more money. Growth gets *more* expensive the bigger you get.

A **loop** is a circle instead of a line. The output of one trip through (a new user, the thing they made, the person they invited) becomes the input to the next trip. Used well, each user you gain helps you gain the next one, so growth compounds instead of constantly needing a fresh push. That's why nearly every fast-growing company runs on loops, not funnels.

You don't have to make *everything* a loop. Some parts of a business really are funnels (a one-time sales process, say), and that's fine. The point isn't dogma. It's to *look* for the loop, because if you find one, it changes the trajectory of the whole thing.

## The famous ones, so you recognize them

Every big tech company runs on loops. Worth knowing the canonical handful, because your app is probably a simpler cousin of one of them:

- **Netflix (a data loop).** You join → it learns what you like and recommends better → you watch more and stay → your engagement and word of mouth bring in more people and more data, which makes the recommendations better still.
- **LinkedIn (an invite loop).** You sign up → you connect your contacts → it uses those to make your first experience good → it nudges you to invite more contacts → they sign up and do the same. They've ridden that one loop for 20 years to a billion users.
- **Uber (a marketplace loop).** More riders make driving more worthwhile → more drivers mean shorter waits and lower prices → which brings more riders. Two sides feeding each other.
- **Substack (a marketplace + content loop).** Writers publish newsletters → those attract readers → some readers become writers → who bring their own readers.
- **Airbnb (several loops at once).** The core: new hosts add places to stay → that draws travelers → demand draws more hosts. Plus smaller ones: listings ranking on Google, guests leaving reviews that pull in more guests, hosts inviting hosts.

Notice none of them grow by "spend more on ads." The product itself does the recruiting.

## The two layers: the big engine and the boosters

Real products have one **core loop** (the big engine the whole business turns on) and several **small loops** layered on top to make it spin faster. Airbnb's core engine is hosts → travelers → more hosts. The SEO loop, the review loop, and the host-invite loop are boosters bolted onto that engine.

For a beginner: find your *one* core loop first. Get that clear before you ever worry about boosters.

### The big-engine types (mostly for when you get bigger)

These are the engines behind massive companies. You probably won't build one on day one, but recognizing them helps you see where you might be headed:

- **Network effects:** the product gets more valuable as more people use it (LinkedIn, a group chat, Fortnite, "everyone I know is on it").
- **Marketplace:** two groups make each other more valuable as more of each show up (Uber's riders and drivers, Substack's writers and readers, eBay's buyers and sellers).
- **Data:** the product gets smarter the more it's used, because it learns from everyone (Netflix's recommendations, search engines).
- **Economies of scale:** it gets cheaper to run per customer as you grow, so you can win on price (AWS, Amazon).
- **Brand:** the name itself gets more pull as more people use it (Apple).

### The booster types (what a beginner actually builds first)

These are the small loops you can design into a V1. They map to the three shapes in SKILL.md, with a bit more detail:

**1. Viral loop, value spread by the user for their own benefit.** Three flavors:
   - *Personal benefit:* you share because it helps *you*, and the other person gets pulled in along the way (sending a Figma design for feedback, sharing a Google Doc).
   - *Financial benefit:* you share because you get something (Robinhood's free stock for a referral, Dropbox's extra storage).
   - *Social benefit:* you share because it makes you look good (early developers telling each other about Stripe to look tasteful; posting a tool you're proud of using).

**2. Content loop, the product's output gets shared or found.** The thing users make becomes public and pulls in strangers. It can be company-made (a content-marketing blog), user-made (Reddit threads, G2 reviews, forum answers), or supply-made (Airbnb listings, Poshmark items), and a lot of it works by ranking on Google.

**3. Paid loop, money out comes back as money in.** You make money, then spend some of it to acquire more users (ads, sales reps, integrations). It's a real loop, but it costs cash and it's the least "free" of the three. Reach for it once you have money coming in, not at the start.

## How to find your loop

Two questions, asked plainly, get you most of the way:

1. **How do new people discover this product?**
2. **Why do the people who use it keep coming back?**

Answer those honestly (ask a few real people if you can, don't just guess from your chair), then match the answer to one of the shapes above. Start with the core engine: who's involved, what action they take, and what that action produces that pulls in the next person. Then, only once that's clear, think about a booster or two.

Your loop is **not always obvious.** Sometimes you have to ship, watch how people actually share you or find you, and discover the loop by surprise. That's normal. Plant the conditions for one, then watch for it.

## Sketch the math (keep it simple)

You don't need a finance degree. For your one core loop, write out the major steps, then make a rough guess at the drop-off between them:

> 100 people land on a public listing → 10 sign up → 3 create a listing of their own → each new listing brings ~5 new visitors...

The one thing you're looking for: does a single trip through the loop bring in *more* than one new trip? If 100 visitors eventually cause more than 100 new visitors, the loop grows on its own. If it causes fewer, the loop leaks and needs help (or you're still in push-it-by-hand mode). Pick the single number that tells you this and watch it over time.

## Four ways to make a loop spin faster

Once you have a loop, these are the levers:

1. **Remove bad friction.** Cut the pointless steps that make people drop out: the long signup, the confusing screen, the dead end. Every step you remove lets more people complete the loop.
2. **Add good friction.** Counterintuitive, but a *little* friction in the right spot deepens commitment: LinkedIn asking you to add your skills, a setup step that makes the product feel more like yours. Friction that increases value, not friction that annoys.
3. **Increase throughput.** Push more people (or more activity) through the loop: fresh content, new reasons to come back, more of the action that triggers the next turn.
4. **Align what you give with what you take.** The magic one. When the value you create for users lines up with how you make money (Robinhood made trading free and grew right alongside the surge in retail investing), the loop and the business pull in the same direction instead of fighting each other.

You're not reinventing the wheel here. You're oiling it.

## The honest caveat

Not every app has a viral, organic loop, and forcing one onto an app that doesn't want it makes the product worse. A spammy "invite 5 friends to continue" wall, a fake referral scheme nobody asked for, these repel the exact people you're trying to keep. If there's no honest loop, don't fake it. Lean on the Phase 6.5 distribution channel instead, and revisit loops once the product has more surface area. A real "I show up in my community every week" beats a fake loop every time.

## Credits

Growth loops as a framework are Brian Balfour and the Reforge team. The loop taxonomy (the big-engine vs booster split, the viral/content/paid breakdown, and the four accelerators) builds on Casey Winters and Kevin Kwok's work in Reforge's Advanced Growth Strategy. Translated here into three buildable shapes and plain language a first-timer can act on.
