I've always wanted to build a product I could sell online.

Last week I did it — a full AI-powered KYC API, live in production,

listed on RapidAPI, with a registration system and usage dashboard.

Here's exactly how I built it.

What is KYC?

KYC (Know Your Customer) is the process of verifying a user's identity.

Every fintech, bank, marketplace, and crypto platform needs it.

Most solutions cost thousands of dollars per month. I built one for free.

What the API does

✅ Face detection and centering check

✅ Liveness detection (real person vs photo of photo)

✅ Age estimation (18+/21+ flags)

✅ Glasses and mask detection

✅ Emotion detection

✅ Background quality check

✅ ID document data extraction (name, DOB, document number)

✅ Selfie vs ID document face matching

✅ Confidence score 0-100

The tech stack

FastAPI — Python REST API

Gemini Vision via OpenRouter — AI image analysis (free tier)

SQLite + SQLAlchemy — database for storing verifications

Railway — deployment (free tier)

The API in…