I built an AI tool that explains legal contracts in plain language. Here's why and how.

Last year I bought a house in Germany. If you've been through a German property purchase, you know what that means: a notary appointment with a stack of documents — purchase contract (Kaufvertrag), land registry extracts, loan agreements, building regulations, and more. The notary reads everything aloud while you sit there trying to follow along.

I'm a developer. I can read complex code all day. But that purchase contract might as well have been in a different language. Dense legal clauses, nested conditions, references to paragraphs in other documents — I understood maybe 60% of it.

Everything worked out, but the experience stuck with me. We all sign important documents — property contracts, employment agreements, NDAs, freelance contracts — and most of us don't fully understand what we're agreeing to. The alternative is paying a lawyer 200+ EUR/hour for what amounts to "is this normal?"

So I built explains.app. You upload a PDF (or Word doc, or text file) and the AI reads it section by section. For each section, you get:

• A plain-language explanation next to the original text

• Risk flags for hidden fees, auto-renewals, liability clauses

• A glossary of legal terms

• AI chat to ask follow-up questions (on the Pro plan)

The tech stack: Next.js 14, Supabase (auth + DB + storage), OpenAI GPT-4o for explanations, Google Gemini for OCR on scanned docs, Stripe for billing, QStash for background processing.

Current numbers: Just launched.

What's next: I'm focusing on improving the AI explanations for employment contracts (they have the most varied structures) and adding more export formats.

Happy to answer any questions about the build, the market, or the tech.