How I'd build Renewal AI for Service Businesses
I'd reach for Next.js on the frontend with TypeScript, FastAPI in the backend for async task handling, Postgres for the database, and Stripe plus Twilio for payments and messaging. I'd use Docker containers deployed to Railway for infrastructure simplicity, Bull on Redis for background job scheduling, and Resend for transactional email. You're looking at roughly 160 to 180 hours of development time to ship from zero to a production-ready multi-tenant SaaS, which at $75 per hour puts the engineering cost around $12,000 to $13,500.
Day-by-day plan
Day 1: Provision JWT authentication schema and set up Postgres row-level security policies for multi-tenant isolation. Day 2: Build Stripe Customer and Subscription models, set up webhook handlers for payment events, cancellations, and subscription updates. Day 3-4: Wire the customer onboarding flow - sign up, email verification, CRM platform selection, initial data sync, Stripe billing tier assignment. Day 5-6: Build the renewal rules engine - date-based triggers, contact frequency rules, customizable message templates, and background job scheduling via Bull. Day 7-8: Integrate Resend for transactional email and Twilio for SMS; build the template editor UI with preview. Day 9-10: Ship the dashboard - renewal pipeline visibility by stage, churn rate trends, revenue forecast, customer settings panel, API key management. Day 11-12: Reverse-engineer and integrate the ServiceTitan and Jobber APIs to pull contract, customer, and renewal date data; handle API rate limits and data schema differences. Day 13-14: Full test coverage on the critical path, staging environment with production parity, smoke tests. Week 3: Onboard first paying customers, monitor job queues and error rates, fix integration bugs in production.
What's hard about this build
ServiceTitan and Jobber expose customer and contract data through APIs, but their data models differ enough that you need branching logic to normalize renewal dates. ServiceTitan stores renewal dates on the contract object; Jobber uses the service plan. Reverse-engineering their pagination and rate limits takes trial and error. Multi-tenant billing in Stripe is a sharp edge: one customer's failed payment webhook cannot accidentally refund or affect another organization's subscription, so the webhook handler needs careful isolation. Compliance adds friction. Twilio SMS has TCPA rules around consent, opt-out tracking, and message frequency, and you need an audit trail for every renewal message sent for SLA proof. The renewal scheduler itself has to handle timezones correctly so a customer in Chicago gets their reminder at their local time, not server time. Finally, there's the displacement problem: ServiceTitan and Jobber already include basic renewal reminders, so the feature isn't novel. You're not selling convenience; you're selling a reason to switch from an incumbent.
What's fast because of AI
Claude scaffolds the entire Next.js and FastAPI project structure, complete with type-safe API client generators and database migrations. Writing comprehensive unit and integration tests normally takes two to three weeks; Claude writes the test suite in four to five days by enumerating edge cases I'd miss - retry logic for failed API calls, timezone wraparound bugs, payment webhook idempotency. Product UI copy - onboarding screens, error messages, template suggestions, empty states - would take me a week to wordsmith; Claude generates polished drafts in an hour. Debugging integration failures is faster: Claude helps trace data through Stripe and ServiceTitan API responses and spots schema mismatches or field name changes. API documentation auto-generates from the OpenAPI spec. The entire development pipeline compresses roughly three weeks of solo work into two.
How I'd hand it off
I'll record a Loom walkthrough covering the admin dashboard, the customer onboarding flow, and how to integrate a new CRM platform. You get a runbook with deployment steps, environment variable setup, database migration instructions, and scaling guidance for the job queue when throughput grows. I'll stay on pager rotation for 30 days post-launch to handle critical production bugs and customer integration issues. Stripe, Twilio, and ServiceTitan API credentials transfer to your account via a secure credentials document. The Linear board will be current with remaining integrations, known limitations, and performance optimizations worth tackling next. Any undocumented architectural decisions get a five-minute sync call.