I Built a Serverless Fraud Detection Pipeline on AWS. Here's What It Actually Costs to Do It Right.

Most cloud portfolio projects look like this: spin up an EC2 instance, deploy a web app, take a screenshot. Done. That tells a hiring manager you can follow a tutorial. This is not that. I built a real-time transaction screening pipeline modeled after how financial institutions actually handle suspicious activity routing. The entire processing backbone costs $2.48/month to run at 500 000 transactions. Here is how it works, why every decision was made, and what it actually costs to secure it properly. The Problem This Solves Payment processors and banks screen every transaction before it clears. A transaction above a defined threshold, or matching a suspicious pattern, needs to be flagged, stored, and routed to an analyst in near real-time. Latency here is not a UX problem. It is a compliance and fraud exposure problem. The architecture needs to handle three things without failing: Ingest transactions reliably, even under burst load Evaluate and persist every transaction regardless of o