I built a tool because I was tired of writing this email:

  "Hi, just following up on my invoice from 3 weeks ago..."

  I ran a small business from 2016 to 2019 and lost it because
  clients didn't pay on time. The stress of constantly following up,
  not knowing what to write without sounding rude, feeling like
  you're begging to be paid — it eventually broke the business.
  I sold at a loss and went back to full-time employment.

  Years later, with an IT background going back to 1993, I looked
  at what was available. Every tool on the market is template-based.
  Same robotic email every time. Complex setup. Priced for enterprise.
  And they all still need you to manually check if the customer
  actually paid.

  So I built Unpaid.

  It connects to Xero, QuickBooks, or Stripe and uses AI (Claude by
  Anthropic) to write genuinely unique payment reminders — starting
  with a courtesy heads-up before the due date, then a 5-stage
  escalation from friendly nudge to final notice.

  What makes it different from templates:

  - If a customer says they've paid, Unpaid verifies it against your
    accounting data automatically. If it can't confirm after 3 days,
    it sends a polite follow-up asking for a payment reference.
  - If a customer disputes an invoice, reminders pause automatically
    and you're notified.
  - If a customer asks for the invoice to be resent, it's resent
    automatically.
  - All alerts and approvals come to your email. You don't need to
    log into a dashboard.

  You can also create invoices directly in Unpaid — they sync to
  your accounting software with your branding, logo, and payment
  link, exactly as if you'd created them in Xero or QuickBooks.

  I tested every feature with live Xero, QuickBooks, and Stripe
  accounts. Registered a sole trader business, used family as
  clients, made real payments with my own credit card. No sandbox,
  no demo mode.

  Stack: FastAPI + SQLAlchemy, Next.js, Claude (Anthropic), APScheduler,
  PostgreSQL, deployed on Railway + Vercel.

  Free 14-day trial at https://getunpaid.io (code PRODUCTHUNT for
  30 days free).

  Would love feedback from HN — especially on the AI email generation
  approach and the verification flow.