Justus Mulli's first 2023 AI products were fast, but not focused enough. After ChatGPT sparked his interest in indie hacking, he built an AI therapist chatbot in about two weeks and abandoned it when the medical angle and ad restrictions looked risky. Then he built a voice-conversation chatbot in about three weeks, liked using it himself, but could not identify a clear target customer.

The third attempt became BlazeSQL. As a data scientist and product owner, Justus knew the annoyance of repeatedly explaining database schemas to ChatGPT just to get useful SQL. BlazeSQL let users add a schema and generate SQL queries from natural language. He built the first version in one to two weeks, posted it to r/SQL, and the post became one of the subreddit's top all-time posts, bringing around 200 account signups within days.

The first subscriber arrived in May 2023, about two months after launch, paying $19.99. Revenue later hit roughly $1,600 at one point, about half recurring and half one-time purchases, before falling when the early traffic faded. Justus then shifted from assuming the product would grow itself to deliberately working on organic inbound and SEO. By October 2023, BlazeSQL was just over $1K MRR and rising steadily.