The Journey
How I built a SaaS in less than 6hrs that got more than 2200+ active users and over 10k+ Subscritions processed
The Engineering
The tech stack that made it all
Next.js + TS ftw
...and a sprinkle of Vercel Functions
...and a dash of my own payment gateway
AI : OpenAI GPT-4o mini
DB : Supabase
hosted on vercel
The Payment Infrastructure
The Infrastructure that powered the whole operation, is on its own, a work of art. No payment gateway in India supported unregistered businesses, espicially unregistered SaaS businesses. The go-to solution, Stripe was not offering UPI. Given the demographics of the users, UPI was the only payment method that made sense... easy to use, no credit cards, no hassle. No one ever wanted to enter their card details on a website even if it was on Stripe's page (obvious kids)
...so that left me with no other choice
I built my own payment gateway
I wanted to receive payments directly to my bank account, and I also needed to verify if the user had paid or not. So I built a system that would get the payment screenshot from gpay, paytm or any other UPI app, and then verify the payment by checking the transaction ID and the amount.
A function will be called with the extracted data from the screenshot, which would verify the payment and activate the subscription for the user. A function that would retrieve my bank statement and cross verify the payment with the transaction ID and amount.
The system was designed to be secure, with multiple layers of encryption and authentication. The payment verification process was automated, ensuring that users could access the tool immediately after making a payment. The system followed an Optimistic Validation approach, where the user would be granted access immediately after making the payment, and the verification would be done in the background during high loads.
Everytime a txn was made, i would get a webhook. And there were 2 types of webhooks I got


This obviously made things easier for me to overview.
The Database
It was the most important part of the whole system. It monitored 2 things mainly.
1. user data
- phone, email, name, password, subscription status, remaining_tokens, total_tokens_used, subscription_expiry, connected_accounts (IPs),
2. txn data
- phone, transaction id, amount paid, payment method, timestamp of the payment, sender
This meant it is easy for me to do any changes to any of the user accounts as all i had to do was filter the user by the phone number and i can change anything i want - all in a single place.
Supabase project dashboard was my admin panel
The Serverless Architecture
The complete system is serverless - from payment management to everything. All. Deployed. As Vercel Functions.
So its safe to say that it costed me absolutely NOTHING to run the whole operation.
The Marketting & Management
Build something that people want, and they will come to you.
...and thats not it all that was to the secret sause.

This was supposed to be my user aquisition cost and the money i spent on marketing. And this. This one screenshot went on to become the justification for switching to a paid model. And the narrative sold. Looking back, this was barly even fraction of the money I made on a monthly basis, and it was the best decision I made. The bill ended up being around $640 that month.
ps: i pulled a big brain move and eod didnt even end up paying for it. So that still keeps our running + investment costs at almost nil.
Sample marketing 101. done right
I aimed in providing the best user experience possible. Direct live support via Discord. Simplified instructions and video tutorials for almost everything.
Dispite all this, i realised that people are still dumb. They still ask the same questions over and over again, even after reading the instructions. When people pay money for something, they just switch off their brains afterwards.
The biggest asset for the whole marketting was - FOMO. The fear is what made people use TT, fear of missing out. Subscriptions were made in clusters - a friendgroup sees one or 2 people using it, and they all want to use it too. And then they all start using it, and then they all start telling their friends about it, and then their friends start using it, and so on. It was a chain reaction that led to the exponential growth of the user base.
Because everyone wanted others too to use it cause they felt scared to be the only one. those who didnt use it were scared that they will be the only ones who wont be using it and missing out.
Why
The Origin story how it all started...
It was more than just a SaaS tool, it was a phenomenon.
a phenomenon that that taught me more than I could ever imagine.