Built a billing platform processing $40M/yr in 14 weeks

The challenge

Northwind's existing billing was a spreadsheet held together by three Zapier flows and a part-time bookkeeper. Every new customer required manual invoicing, dunning was non-existent, and reconciliation took two days a month. As the client base grew from 20 to 200+ accounts, the founder spent 30% of her week on billing fire drills. They needed a real platform — fast — without a 6-month rewrite that would burn through runway.

Our approach

• Spent the first two weeks scoping ruthlessly: a single tenant model, one currency, one payment method on day one. Everything else was v2. This let us ship a production-grade MVP in 14 weeks instead of the 6–9 months the founder had budgeted for.
• Built on Stripe Connect Express for payment rails so we never touched card data or PCI scope. Used Connect's account-onboarding flow to let Northwind's customers self-register without KYC friction.
• Multi-tenant Postgres with row-level security enforced at the database layer from week one. Every query was scoped by tenant_id automatically — the admin dashboard and the customer self-serve portal shared a single schema with zero risk of cross-tenant data leaks.
• Designed a declarative billing engine that mapped subscription plans, add-ons, discounts, and usage-based line items into a single ledger table. Invoice generation became a materialized view refresh instead of a fragile cron job.
• Built a three-stage dunning pipeline (email → SMS → account hold) triggered by Stripe webhook events. Each stage was configurable per tenant, and the system auto-collected 95% of delinquent invoices without human touch.
• Weekly Friday demos to the founder, starting with a clickable wireframe in week one. By week six there was a working subscription + checkout flow in production handling test traffic. Every demo ended with a ranked list of what was blocking the next milestone.
• Wrapped everything in end-to-end Playwright tests covering the full billing lifecycle — signup, plan change, invoice generation, payment failure, successful dunning recovery — so regression risk stayed near zero as features stacked.

The outcome

Launched at week 14, on the exact price quoted in week 2. In the first year the platform processed over $40M in subscription revenue with 99.99% uptime and zero billing incidents requiring customer credits. Invoice generation dropped from two days to under an hour. The dunning pipeline auto-collected 95% of late payments, and the founder went from 30% of her week on billing to less than an hour.