
Serhii BaraniukFounder of Writing9
$12,000 monthly revenue
Serhii Baraniuk writes…
I built Writing9 to help people improve their IELTS Writing skills.
IELTS = International English Language Testing System.
Back when I was learning English, I struggled with writing and wished there was a tool that could give real feedback – so I made one.
Writing9 checks essays, points out mistakes, and gives an estimated IELTS band score. It’s like having a personal tutor, but way faster and more affordable. Thousands of people use it every day…
Today, we bring in around $12K/month
Looks like he launched it in 2020 as a basic app which you could probably vibe code today 
More examples of people earning good money by helping others prep for specific exams…
Her 3-Hour Crash Course Earned $1 Million in 7 MonthsNiche Study Guide Selling on Amazon = $8.7K/Month ProfitWhat exams have you taken in the past?
Might be an opportunity to create an app / course / study guide there 
Or perhaps even start off as a one-on-one tutor.
Published on August 04, 2025 06:21