How I built a SaaS that sends AI-written Stripe reports every Monday — and what I learned

#showdev #saas #aws #python

I've been building Autoreport for the past few months alongside my day job. The idea was simple: every Monday morning, get a PDF in your inbox with your Stripe numbers from the previous week — no dashboards, no manual work.

Here's how I built it, the stack I chose, and the lessons I learned along the way.

The problem

I kept opening Stripe every Monday to check the previous week. Revenue, payments, new customers. It wasn't hard — just friction. And because it required effort, I kept skipping it or doing it badly.

I wanted the numbers to come to me, not the other way around.

The stack

The entire backend runs on AWS, deployed with Terraform:

Lambda (Python) — one function per stage of the pipeline: data extraction, AI narrative generation, PDF building, email delivery
EventBridge — triggers the pipeline every Monday morning
S3 — stores raw Stripe data and generated reports
DynamoDB — tenant registry
SES — email delivery
Secrets Manager — stores each customer's Stripe API key
Bedrock (Claude Haiku) — generates the AI narrative from the weekly metrics
API Gateway + Lambda — handles Paddle webhooks for subscription management

The landing page is a static site on Netlify. Payments go through Paddle as Merchant of Record.

How it works

Customer subscribes via Paddle checkout
Automated email via SES asks for their Stripe read-only API key
Customer replies with the key, I register them manually via a script (intentionally simple for beta)
Every Monday, EventBridge triggers the pipeline per tenant
Lambda pulls Stripe data, sends it to Bedrock, builds a PDF, delivers it via SES

What surprised me

Bedrock prompt engineering took longer than expected. The first version of the AI narrative was alarmist — "critical concern", "immediate attention" — for perfectly normal week-over-week fluctuations. I had to be very explicit in the prompt about tone, context, and when strong language is actually warranted.

The Merchant of Record route (Paddle) was the right call for avoiding tax and VAT headaches as a solo founder in Spain. The approval process took a few days but was worth it.

What's next

Right now it's in beta. If you run a SaaS on Stripe and want your week summarized every Monday without lifting a finger, give it a try at autoreport.dev.

Happy to answer any questions about the architecture or the build process.