The old way to prototype meant a designer for mockups, then a developer to code it, then testing. Three weeks, multiple people, slow loops. The new way is you and Claude Code, iterating for an hour, with something testable today. Here is the exact flow, minute by minute.
Minutes 0 to 15: frame, then hand off
Spend the first five minutes getting crystal clear on the problem. Write a two to three sentence problem statement covering who the user is, what job they are doing, and the cost of them not doing it well. List the steps they need to complete, not screens, steps. Name the constraints. Then decide scope by writing down what you will not build. For an onboarding wizard example, that means "we will not build real Salesforce integration, we will use a mock API."
Then open Claude Code and describe the problem and user journey. Ask for a working web app where each step is a clear screen, it feels like a real product with no placeholder text, and the API calls are mocked with fake data. Ask it to deploy to Vercel or Netlify so you get a shareable link. Claude builds a functional prototype in about two minutes. Click through it immediately and jot your first reactions.
Minutes 15 to 45: iterate and make it real
Now refine with specific prompts, not a rebuild. Tell it exactly what feels off: "the data mapping step is confusing, users do not know what source field versus destination field means, add inline help text." Add loading states, a progress indicator, and form validation so it stops feeling like a mockup. Walk a specific user scenario and smooth the happy path. Check it on a phone-sized viewport.
Then swap dummy data for realistic data that matches your actual schema, and add two or three edge cases: what happens with 500 fields, a field mapped twice, an unexpected format. Add one moment that makes it feel real, like showing a preview of the report they just set up.
Minutes 45 to 60: deploy and share
Do a final run: no console errors, mobile works, clear error messages, a success screen that explains what they just did. Get the shareable link and send it to three customers with a short note asking whether the flow makes sense, what is confusing, and whether they would actually use it.
This is 10x faster than design, build, review, redesign, rebuild. A prototype with rough edges that teaches you something beats a beautiful mockup that is never tested. Pick one feature idea this afternoon and run the workflow.