Automated invoice follow-up system for plumbers and trade contractors

This is a $14K/month proven business. A developer found that Reddit comment, built a simple invoice reminder tool specifically for plumbers, and now earns $14K/mo. The playbook is public. The market is nowhere near saturated.

Existing invoicing tools like FreshBooks and QuickBooks technically have reminder features - but they send one generic email and stop. Trade contractors need escalating sequences: polite reminder at 7 days, firm follow-up at 14 days, "this will go to collections" warning at 30 days, and a small claims court template at 60 days. The tone matters. The timing matters. And it needs to work via text message, not email, because plumbers don't check email.

Build a standalone tool that connects to QuickBooks, FreshBooks, or works independently. Contractor creates an invoice. The system handles everything after that. Escalating reminders via SMS. Dashboard showing who owes what and where each invoice is in the follow-up sequence. One-tap to pause reminders if the customer calls to arrange payment.

Price at $39/mo for solo operators, $79/mo for small shops. The ROI is absurd - if the tool collects even one $500 invoice that would have been forgotten, it pays for itself for the entire year. Trade contractors understand this math immediately.

At 5,000 subscribers averaging $50/mo, that's $3M ARR. Expand from plumbers to electricians, HVAC, roofers, landscapers - every trade has the same problem. The proven revenue from the original builder validates the entire category.