Invoice Chaser — Automated Payment Reminder SaaS (Source Code)

Invoice Chaser is a complete, working SaaS application that automatically chases late invoices for freelancers, agencies, and small service businesses — so they stop losing cash flow to manual follow-up.

What’s included:

– Full source code (Next.js App Router, TypeScript, Tailwind CSS)

– Prisma ORM data layer (SQLite for local dev, easily swapped to Postgres)

– Email/password authentication with secure sessions

– Client and invoice management (create, edit, mark paid)

– Automated reminder engine: escalating friendly to firm to final-notice emails at -3, 0, +3, +7, and +14 days relative to the due date, with no duplicate sends

– Dashboard with outstanding balance, overdue totals, and per-invoice reminder history

– Configurable reminder schedule per user

– Seed script with demo data so it looks alive immediately

– Full README covering setup, run, and deployment steps

What you’ll need to add for production:

– A transactional email API key (e.g. Resend) — the app dry-runs emails to the console until you add one

– A daily scheduled job to trigger reminders (cron, Vercel Cron, or Task Scheduler)

– Postgres for a production database

– Stripe integration if you want to charge your own customers a subscription

Ideal for developers or agencies who want to launch a niche invoicing SaaS without building the reminder engine and data model from scratch.