How Sacha got the first 10 paying users for his AI thumbnail SaaS

Meet Sacha Dumay.

Sacha is a 32 year old French indie hacker and new dad living in Seoul, South Korea. He describes himself as a total geek who loves AI, data science, and playing padel.

Sacha co-founded ChatNode in 2023 and successfully exited in mid-2024 with a sale exceeding $200,000. Previously, he was CTO at a trading firm in Chicago.

Currently he is working full-time on AI thumbnail.

The story told by Sacha Dumay

Going solo

In 2025, I decided to go solo.

With little experience in marketing or design (but strong backend and AI dev skills), I jumped into the solopreneur life.

After launching a YouTube channel to document my build-in-public journey, I quickly saw how painful it is to make good thumbnails, especially as a non designer. Templates were boring or didn’t match personal brands.

That’s why I built AI Thumbnail, a tool to help YouTubers and marketing agencies create viral thumbnails using AI. It’s for brainstorming ideas fast, skipping the designer, and even injecting your own AI generated face into the image.

Super fun to build.

Brutal feedback

After one month of building, I had a working V1 and shared it with a few YouTuber friends. Feedback was great… but brutal.

“Talk to your users. Don’t be afraid to throw it all away and start again. That’s your edge.”

I ended up redoing everything.

Once V2 was ready, motivation dipped. Around the same time, GPT image-1 model launched. Perfect timing. I jumped on the buzz, upgraded the app to use GPT 4 image support that same day, and launched on Product Hunt right after.

With zero prep and no paid marketing, AI Thumbnail got to Top 8 of the day on a Friday. Just enough to get featured on the homepage and drive traffic (see screenshot below).

I got this personal rule:

“If 1,000 unique visitors don’t get me at least 1 paying user, the project might not be worth it.”

Luckily, a $49.00 Stripe notification came in. Then a few more. That was enough validation to go all in.

The business model

AI Thumbnail is mainly based on a subscription model. But to get the first few clients I sold 49$ lifetime deals (with a credits limit).

Marketing

My current challenge is trying to get consistent traffic. Here’s what I’m testing.

Building in public

I’m building in public on X (example below) and YouTube. It’s fun - but the audience is not super targeted.

Medium

Every few weeks I post on Medium - example below.

How I Got SEO Traffic Fast by Launching a Free Tool

YouTube Shorts and TikTok reels

I create short video content for YourTube Shorts and TikToc reels. The results are pretty good - but I’m not 18 anymore 🙂

This is an example of one of my YouTube Shorts. I post the same content on TikTok.

Search engine optimization

I’m investing in SEO. It’s slow, but finally starting to work.

I have built two free tools (links below) to bring organic traffic and shared them on Hacker News. They helped me a lot speeding up the indexing by Google.

• Thumbnail Tester

• YouTube Thumbnail Resizer

I also have an automated blog post that publishes one blog post per day.

I am constantly increasing my domain rating (DR). It was 0 just two months ago and now it's up to 24. Mostly from guest posts, directories, launch pads etc.

Current status

So that’s how I crossed $500 in revenue with just 3,000 unique visitors and a bit more than 10 paying users - and growing.

Screenshots from AI Thumbnail

If you want to reach out to Sacha Dumay, you can find him on X.