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$25K/Month SaaS Built for Ancient Accounting Software

  • Danny Nemer

  • Solo SaaS Founder
  • $25,000 monthly recurring revenue

🤑 Danny Nemer built a solo SaaS that does $25K/month – with zero outbound sales.

His product? Conductor – a modern API for integrating with QuickBooks Desktop, an accounting system that’s 15+ years old and has no web API.

Tiny market. But people who need it go looking for it.

📝 From a recent post

I only had two customers for the first 1.5 years, but that was primarily because it took so long to build so many surfaces pre-GPT-3.5.

Way faster and easier to build something like this now with AI 🤖

Today Danny spends only about 3 hours a week on the business.

He’s turned down two separate $1M acquisition offers because his earnings are higher if he just holds 🤯

What old, clunky system could you build the modern API for?

  • Search Stack Overflow or Zapier’s forums for “no API” complaints.
  • Look for old desktop software that’s still widely used.

That’s where the next $25K/month SaaS idea might be hiding 😎

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Updated: April 4, 2026

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