How a Weekend App I Built for My Wife Became $2,500/Month in Passive Income

In 2020 I built a mood board editor for my wife for her interior design projects.

It runs now fully passive:

• zero employees

• running costs under 100eur (firebase, hosting, ai models)

• automatic payment and invoicing

• no support needed

• last product update was 6 months ago

It was not a fast win:

• 2020: launch, no signups for months

• 2021: first subscribers

• 2022: first few hundred dollars per month

• Aug 2025: peak with almost 8k during the AI hype

• now: settled at $2,500

Revenue dropped after the hype settled, but the product does not need me. That was the point.

If I compare it to my real estate rentals it is even more passive. No tenants and less things breaking.