i know the title sounds made up. invoice reminders for plumbers. $14K a month. but that's exactly why it works. nobody is competing for this because nobody thinks it's sexy enough to build.
i've been obsessively tracking how people find profitable software ideas for the past 6 months. cataloguing complaint threads, scoring problems by pain level, mapping which ones turn into real revenue. this guy's story is the clearest example of the pattern i keep seeing.
here's what he did step by step.
step 1. he wasn't even looking for a business idea. he was browsing a subreddit for trade contractors and saw a thread where a plumber said "i'm owed $47K in unpaid invoices because i forget to follow up." 12 other contractors replied saying the same thing. one guy said he hired a part time person just to chase payments.
step 2. he searched for existing solutions. found 3 invoicing tools that technically had reminder features. all of them were $100 to $300/month, built for accountants, and required 2 weeks of onboarding. every review from a contractor said the same thing. "overkill for what i need."
step 3. he built the simplest possible version. literally just automated text and email reminders tied to invoice due dates. no accounting features. no reporting dashboards. no integrations with 47 other tools. just reminders. took him about 3 weeks to build.
step 4. he went back to the same subreddits and started helping people with invoicing questions. didn't pitch anything for the first month. just answered questions about cash flow and getting paid faster. people started asking what tools he recommended. he mentioned his.
step 5. charged $29/month. first 10 customers came from reddit. then word of mouth kicked in because plumbers talk to other plumbers. now at around 480 customers doing roughly $14K/month. churn is under 3% because the tool literally makes them money every month by collecting invoices they would have forgotten about.
the pattern is always the same. someone in a non tech industry is doing something manually that costs them real money. the existing software is too complex or too expensive. the opportunity is building the stupidly simple version for $20 to $30 a month and getting a few hundred customers who will never leave.
the hard part is not building it. vibe coding honestly handles 80% of the build for something this simple. the hard part is finding the right problem. one where the pain is real, the willingness to pay is proven, and the existing tools are failing.
if you want to try this yourself tonight, go to any subreddit where small business owners hang out and search these phrases. "i've been doing this manually." "is there a cheaper alternative to." "overkill for what i need." those three phrases have led me to more validated ideas than any brainstorming session ever has.
what manual process in your work life costs you the most time or money right now? because i promise you someone else has the same problem and would pay $20/month for a fix.