I've read a lot of “how I made $X” posts, and most of them skip the real work. They show the number and a few screenshots. They leave out the part where the work happened, and that is the only part you can learn from. I always close those tabs feeling like I saw the best moments of a game when I needed the full video.
So I wrote the full story.
Kortex is a Chrome extension that adds the features Gemini Notebook (formerly NotebookLM) is missing: exports, imports, search, folders, bulk actions, and a podcast feed for Audio Overviews. I built it alone. I had no paid ads, no growth team and no co-founder to share the stress. I had one person, a clear wedge (a gap in a product people already use), and a way to reach people that I built one plain step at a time, often at hours I am not proud of.
The question I get most, in DMs, in Reddit replies and over coffee, is some version of: “The product is fine, but how do I get customers?” That question is the reason this book exists. So the book focuses on it. It covers how I found my first users, how I earned trust as an unknown solo developer, and what happens in someone's mind in the three seconds before they decide to pay. Every chapter gives you the tactic and then the real story behind it: how I found it, what I almost did instead, and what happened when I shipped it. The tactic is the easy part. The reasoning is the part worth copying.
The one-line version
Find a tool people already love and build the thing it is missing. Talk to the people who need it, one by one, until you understand them better than they understand themselves. Then build every price, page and pitch around how people decide to spend money.
Proof from inside
The channels behind chapters 07 & 09 — proof, not theory
Give-first on Reddit
Creators on YouTube
Hundreds of thousands of views, earned with answers and honest demos — never a paid ad. The exact playbooks are in chapters 07 and 09.
What's inside
Three parts. Fifteen chapters.
Part I is the foundation: the plain but important decisions most founders rush past. Part II is the part you probably want most: how to get customers. It is the longest section on purpose. Part III is everything that turns a visitor who likes you into a customer who pays you.
Part I— The Foundation
01
The wedge: pick a host, not a market
02
How your customer actually thinks
03
Build a product that does the marketing for you
04
The ‘aha’ moment: when a visitor becomes a customer
Part II— Getting Customers
05
Your first 100 users: do things that don't scale
06
Go where your people already gather
07
The give-first engine: Reddit, content & SEO
08
The launch: treat it as a campaign, not a day
09
The creator engine (where the real money came from)
10
Three quieter channels that punched above their weight
Part III— Turning Visitors Into Revenue
11
What makes people pay
12
Pricing psychology: design the choice, not the number
13
The trust stack: why people trust a one-person company
14
Keep them: retention is the real growth engine
15
The whole playbook, condensed
Part One
I
The Foundation
No growth tactic in Part II works if you get this part wrong. First you need the right product in the right place. You also need to understand the one person you are building for better than they understand themselves.
01
The wedge
Pick a host, not a market.
For about a week I had two browser tabs open that seemed to argue with each other.
One was a half-built “second brain” app that I worked on at night, the kind of thing every developer tries to build at some point. The other was Gemini Notebook, which I used almost every day for my own research. And every day it made me want to throw my laptop. I would spend an hour building a great notebook full of sources and insights. Then I had no way to get any of it out. Ideas went in and never came out.
One night I closed the second-brain tab for good. The idea was not bad. I finally saw what the two tabs were telling me. The app I was building meant paying Google's ad prices, forever, to convince strangers to want something they had never heard of. The app I was frustrated by already had millions of people inside it. Many of them were as annoyed as I was about the same missing feature. One path is a fight. The other is a door someone left open.
So I built a one-click export and shipped it as a Chrome extension that works inside Gemini Notebook. Within a few days the reviews started. One of them has stayed with me: “no Gemini Notebook user should be without it.” You do not get a review like that when you have invented demand. You get it when the pain was already there and you solved it. I did not create the market. I stepped into one that Google was already paying to fill.
★★★★★
“Love! love! love! — and I'm only using the free version. Huge time saver — no Gemini Notebook user should be without it! I'm definitely considering the Pro version once I get my business beyond the early start-up stage.”
Jenni Duncombe · Feb 19, 2026 · Chrome Web Store review
That decision, where to stand, did more for the $200K than any clever tactic later in this book. I think of it like a small fish that rides along with a shark. You attach to something bigger that is already moving, and it pulls you along.
Manufacture demandA war.
Create awareness. You pay for all of it.
Convert
Borrow demandA doorway.
Host already paid
Convert & build the product
Where your energy goes. If you borrow demand, almost all of it goes to the part that makes money.
Why it works
Borrowed demand. Every time Google ships a Gemini Notebook feature or a creator posts a video, a new wave of “how do I do more with Gemini Notebook” searches arrives. You did not pay for any of that traffic. You are just standing where it comes through.
Pre-qualified pain. Everyone inside Gemini Notebook has already decided AI research tools are worth their time. You are not starting with a skeptic. You are helping someone who already loves the category, which is a much shorter and warmer talk.
A built-in surface. Your product shows up inside the thing they already opened. So reaching people and building the product stop being two separate jobs. A solo founder rarely gets that for free.
A moat made of annoyance. Big platforms are slow to ship “nice-to-have” features. The gap between a great demo and something you can use every day is your space. It stays open much longer than you would expect.
The risk, said out loud
I will not pretend this has no risk. The host could build your feature next quarter or change the rules overnight. Then your door would be closed. I lost some sleep over it early on. My answer is the whole of Chapter 12: own an email list and a brand. Then, even if Gemini Notebook changes, the relationship with the customer is still mine. You rent the land. You own the seeds.
The test for your own wedge
Run a candidate idea through these four questions
Question to ask
If yes…
If no…
Is there a popular product whose fans complain in public?
You have a host. Build the missing layer.
You will have to create demand. That is expensive and slow.
Can you ship the #1 complaint as a v1 in weeks, not quarters?
Ship it. Speed is the only moat early on.
Narrow the scope until you can.
Will the host's own growth pull you along for free?
You found a tailwind. Ride it.
You will always be working against the current.
Can you reach the host's users without the host's permission?
You have a distribution path. Go.
Think again. You depend on the host, and you have no say.
Unlock the four questions in the full playbook
The takeaway
The biggest lever in this whole story was not a growth tactic. It was choosing to attach to a product people already loved, instead of launching another AI note app into a crowded market. Borrowed demand, users who already want it and a place inside the host beat building alone, every time you can do it.
02
Know the one human
How your customer actually thinks.
For a few weeks my landing page was aimed at “anyone who uses AI,” and almost nobody signed up. I stared at the analytics and tried to find what was broken. The copy was clean. The product worked. People just left.
What fixed it was not a better headline. I gave up on “anyone” and wrote to one specific person instead. I called her Riya — a grad student who'd fallen hard for Gemini Notebook, had about forty notebooks, and had just hit the point where the magic stops being easy to use…
The day I rewrote the whole page as if I were talking only to Riya, in her words, about her problem of forty messy notebooks, more people signed up. That lesson changed everything: a message for everyone reaches no one. So the first real job is to answer one question in exact detail—
Chapter 2 continues in the full playbook
+9
The rest of the playbook
Nine more chapters, in the full book.
You just read the first chapter in full, and chapter two is already pulling you in. Here is what waits in the complete edition: the exact steps that turn users who love a free product into paying customers.
Locked
Chapter 11
How to get people to pay
From loved and free to paid
Thousands of happy free users and almost no revenue taught me the six triggers that move someone from "great, free" to a paid plan. I start with the one most founders get backwards…
Locked
Chapter 12
Design the choice, not the number
Anchor · decoy · charm · loss-aversion
I stopped picking a price and started designing the choice around it. That meant the anchor that resets expectations, the decoy that makes the middle plan feel safe, the charm digit, and the loss-aversion line that…
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Chapter 05
Get your first 100 users by hand
Conversations are R&D and marketing at once
Doing it by hand is the point. I found the first hundred users one message at a time. Every conversation was also product research, copy testing, and…
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Chapter 06
Go where your people already gather
Relevance crushes reach
Reach is a vanity number. What moved installs was showing up in the three small communities where the exact people who needed this already spent their…
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Chapter 07
The give-first engine
Give value 10× before you promote once
Before I ever linked the product, I spent weeks just being useful in public. The ratio of helping to promoting that worked, without getting me flagged, was…
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Chapter 09
The creator engine
Trust transfer that can’t lose
One creator in a small niche did better than any ad I ever considered. The affiliate deal I used meant the marketing spend could not lose money, because…
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Chapter 10
Three quieter channels that compound
Store ASO · cold email · build-in-public
Three plain channels added up to most of my volume: treating the store listing like a landing page, cold email that still felt personal at scale, and…
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Chapter 14
Retention & the list you own
Ship weekly · own the channel
Getting the sale is only the start. Shipping something visible every week and owning an email list is what turned one-time buyers into people who…
Unlock the full Growth Playbook
All 15 chapters — the complete system that took Kortex from 0 to $200K, with every story, table, and tactic.
