Build a Schema Markup Validator with Claude Code

Build a Schema Markup Validator web app. People search for "schema markup validator" about 9,500 times a month, plus related searches like "schema markup tester", "structured data validator", "google schema validator". The goal is a tool that ranks for those searches and makes money.

What it should do:
Build a schema markup validator with URL input and code editor. Include schema type detection, error highlighting with line numbers, and fix suggestions. Show validation results with pass/fail status and Google preview. Add schema type selector and common templates. Include bulk URL testing and export reports. Focus on getting basic validation working first.

How to build it:
1. Read this folder first. If it is empty, set up Next.js (App Router, TypeScript, Tailwind). Write a short PLAN.md with the pages, components, any library or API you need, and what you are leaving for later. Then build.
2. Put the tool itself on the homepage so a visitor can use it within seconds, with no sign-up. Do the processing in the browser where you can, so it is fast and cheap to run. Look at how Google Rich Results Test, Schema.org Validator, Merkle Schema Markup Validator do it and make ours simpler and faster.
3. Make it rank. Use "schema markup validator" in the title tag, H1 and meta description. Under the tool, add a short how-to and an FAQ with FAQPage schema, and add a sitemap and robots.txt. Scaffold these programmatic pages from one template and a data file: /validate-[schema-type]-markup, /schema-validator-for-[cms], /[industry]-schema-markup-guide.
4. Monetisation: Freemium: 5 validations/day, $15/mo unlimited + reports. Add a pricing page and the free usage limit, and leave Stripe checkout as a clearly marked stub with the environment variables it needs.
5. Run it locally and test the main flow end to end, including edge cases like empty input and very large files. Fix what breaks, then finish with a summary of what works, what is stubbed and how to deploy it to Vercel.

Paste it into Claude Code in an empty folder. It plans first, so read PLAN.md and steer before it starts building.