Show HN: I built an EU VAT API using only ChatGPT

[passenger09]

I didn’t start this project because of a business need. I just wanted to see how far I could get if I tried to build a “real” SaaS using only ChatGPT and AI tools.

The result is Vatify: an EU VAT validation & calculation API. It can: – Validate VAT numbers (VIES lookup) – Return VAT rates for EU countries – Calculate invoices (net/gross, B2B/B2C, reduced rates, etc.)

I’m not sure if this is a real business yet (there are competitors, and SEO is slow), but I learned a lot: – Most of the backend and endpoints came from ChatGPT – Even the docs, landing page, and logo were AI-assisted – The hardest part was not coding, but figuring out how to make it useful for others

Demo: [https://vatifytax.app](https://vatifytax.app)

I’d love feedback from HN: – Is this interesting enough as a niche? – Would you trust a small tool like this vs. bigger incumbents? – Any ideas where to find the first real users?

Even if it doesn’t turn into a business, it was a fun experiment. Curious if anyone else here has tried building a SaaS “AI-first” like this?