How I'd build Riverine
I'd reach for Next.js on the frontend with TypeScript, FastAPI in Python for the backend, Postgres with Prisma for the database layer, and Stripe for billing. For bank integrations, Plaid is non-negotiable despite the trust friction. The forecasting engine runs async via Celery, pulling historical transactions and running them through a statistical model. I'm looking at roughly 350-400 hours for a production-ready launch - call it 10 weeks working solo with steady momentum. That's right at your budget at $75/hr, assuming no major pivots mid-build.
Day-by-day plan
- Day 1-2: Provision NextAuth for multi-tenant user authentication, build tenant isolation at the database schema layer (tenant_id on every table), and create the core user and business entities in Postgres. This is the foundation everything else bolts to.
- Day 3: Integrate Stripe: set up three subscription tiers, wire webhook handlers for subscription lifecycle events, and implement free trial logic (14 days, then billing-required).
- Day 4-5: Build the Plaid OAuth flow. Handle the credential exchange securely, implement transaction history sync, and write the ETL to normalize transactions into a standard schema. This is where trust is built or lost.
- Day 6: Build the main dashboard UI: transaction list, current balance card, and a forward-looking cash flow chart using Recharts. Keep it clean and fast - no lag.
- Day 7-8: Implement the forecasting engine in FastAPI. Ingest 90 days of transaction history, run it through Prophet or a simpler statistical model, and generate a 90-day forward projection. Trigger this async via Celery after each bank sync.
- Day 9: Wire the in-app cash flow alert system: when projected balance dips below a user-set threshold, send an email via Resend and show an in-app notification. This is the hook that converts free users to paid in week 1.
- Day 10: Build the free trial onboarding - three screens (connect bank, enter business details, view forecast). Keep friction minimal.
- Day 11: Prepare assets and documentation for QuickBooks App Store and Xero marketplace submissions. Generate screenshots, write the listing description, and finalize the privacy policy.
- Day 12-13: End-to-end testing, Sentry and DataDog setup for production monitoring, and bug fixes.
What's hard about this build
The biggest friction is the trust problem. SMB owners see "connect your bank" and immediately think about fraud risk, even though Plaid is the industry standard. Your onboarding needs to be bulletproof: clear explanation of what data you access, explicit retention policies, and zero-friction credential handling. Second, forecasting accuracy matters. Financial data is messy - category inconsistency, one-off expenses, seasonal volatility. A bad forecast kills credibility faster than no forecast. Third, you're competing against "good enough" incumbents. QuickBooks, Wave, and FreshBooks all have native cash flow features. Most SMBs never fully use them, but at the demo stage, that objection will come up. You need a crisp explanation of why your forecasts are simpler or more actionable than what they already have.
What's fast because of AI
Claude compresses the scaffold and boilerplate phases by 60-70%. I'd have the entire API structure, Postgres schema, and component library generated in a day instead of three. For Stripe and Plaid integrations, Copilot handles the boilerplate; I review and customize for your specific flows. The forecasting model benefits too - Claude enumerates edge cases (zero-balance weeks, seasonal patterns, closed accounts) and helps me write defensive validation logic. The biggest win is copywriting. Onboarding microcopy, email alert templates, and your demo script take a week normally. Claude drafts these in a few hours, then I iterate on tone. Debugging also accelerates: I paste Stripe webhook errors or Plaid sync failures into Claude, and it pattern-matches to known issues and solutions.
How I'd hand it off
I record a Loom walkthrough of the full user journey, the admin panel, and monitoring dashboards. You get a deployment runbook: how to push to production, manage Stripe and Plaid credentials, and troubleshoot Celery failures. I stay on pager rotation for the first 30 days - if something breaks in production, I fix it. All infrastructure access, database credentials, and third-party API keys transfer to your vault before I step back.