Picture this: you launch an AI product in three weeks, and a year later it has brought you more than 700,000 rubles. That's exactly the success story Oleg Stefanov told about his project Fanfy Studio.
Who he is
The hero of our story is Oleg Stefanov, an indie developer who launched Fanfy Studio a year ago. It's a service that generates fanfiction with neural networks. The idea is simple: the user enters a universe and their own premise, and the service produces endless fanfiction on demand. Oleg's starting point was the desire to test a hypothesis fast and build a working product using modern AI tools.
How he did it
Oleg built Fanfy Studio in just 3 weeks. The key tools were Cursor for coding and the Sonnet 3.7 model for text generation. After launching in May 2025 the service started producing passive income. User and sales growth was gradual, with noticeable jumps after video posts and promotion on Telegram sozai.app.
To cut costs Oleg switched the generation model to the cheaper Gemini 2.5 Pro. A significant step was finding and fixing a payment vulnerability that let users get an unlimited number of chapters after paying for a subscription just once. After closing that hole and moving to a Pay as you go model (users could buy chapter packs without a subscription), sales grew substantially sozai.app.
In October Oleg localized the site into English, Spanish and Portuguese to widen the audience. He also makes heavy use of neural-network aggregators such as Syntx to save money and simplify working with AI tools. For further growth he plans to boost SEO traffic by adding a new section on the site for reading public fanfiction sozai.app.
The numbers
- Total revenue for the year: more than 700,000 rubles sozai.app.
- Net income: 200,000-250,000 rubles (roughly $2,500-3,000) per month sozai.app.
- Development time: 3 weeks sozai.app.
- Site visits: a little over 20,000 sozai.app.
- Users registered via Google: 2,600 sozai.app.
- Team: 1 person (Oleg Stefanov).
What to take away
- Speed to launch wins: Oleg showed you can build a working AI product in a matter of weeks using vibe coding and modern tools. You don't have to wait for the perfect moment to start.
- Cost optimization is the key to profit: switching to a cheaper generation model (Gemini 2.5 Pro) and fixing the payment vulnerability fed straight into net income growth. Keep looking for places to improve the project's economics.
- Going global widens the market: localizing into several languages opened up a new audience and was an important step toward scale. Think about the world market from day one.
- SEO and content are a long game: the plan to build a section for reading public fanfiction shows an understanding of how much organic traffic matters. It's an investment that pays off over time. If you want to repeat this kind of success faster, without assembling everything by hand, the qvib.pro engines offer ready-made rules and roles for vibe coding so you can focus on your unique idea.