AI-native prototyping, on a real iPhone.
AI-native prototyping is designing by describing: you tell an AI coding agent what the app should do, and it builds a working prototype you can use, instead of drawing static frames and linking them. Prototo is the AI-native prototyping tool that runs natively on real iPhones. Describe it to Claude Code or Codex, hit Publish, and anyone opens it from a link in the free Prototo app. No TestFlight, no builds.
What makes a prototype AI-native
In an AI-native workflow the prompt is the design tool. You describe a screen, a flow, or a change ("make the header collapse on scroll"), and the agent writes it. You judge the result by using it, then describe the next change.
Most AI prototyping tools output a web page. That is fine for dashboards and websites. For an iPhone app, a web preview gets the feel wrong: scrolling, gestures, keyboards, haptics and system materials all behave differently in a browser.
Why native on a real device matters
- Real iOS scrolling, swipe-back, sheets and gestures, because it is a native app.
- Real haptics and the real keyboard, which never show up in a browser preview.
- Apple's Liquid Glass and system materials on iOS 26 and later.
- The person testing it holds it in their own hand, on their own phone.
Why no one else ships it to a phone this easily
Until now, getting a native prototype onto someone else's iPhone meant a developer account, code signing, an upload to TestFlight, processing, beta review and invites. Days of friction for a prototype you might throw away tomorrow.
With Prototo you click Publish. You get a link and a QR code. Anyone opens it in the free Prototo app on iPhone and the prototype runs natively. Links are permanent, and republishing updates the same link.
How it works
- Prompt: describe your app to Claude Code or Codex inside Prototo Desktop on your Mac. A live iPhone preview updates as it builds.
- Publish: click Publish to get a link and a QR code.
- Preview: anyone opens the link on their iPhone with the free Prototo app. It runs natively.
Who it is for
Product designers who want to test an iPhone idea as a real app, design leads who need stakeholders to feel a flow instead of watching a recording, and anyone who misses Play. You do not write code: the coding agent does. You need a Mac with Apple Silicon, Xcode (free) and a Claude Code or Codex plan you already pay for.
Questions
What is AI-native prototyping?
AI-native prototyping is building a prototype by describing it to an AI agent in plain language, then refining it by using it and describing changes. The prompt replaces the canvas. Prototo applies this to iPhone apps: the result is a native iOS prototype, not a web page.
What is the best AI prototyping tool for iPhone apps?
For iPhone apps, Prototo is built for the job: it produces native iOS prototypes from Claude Code or Codex and shares them as a link that runs natively on any iPhone through the free Prototo app. Web-first tools like Figma Make, Magic Patterns and Google Stitch are better suited to websites and web apps.
Can I share an iPhone prototype without TestFlight?
Yes, with Prototo. Click Publish in Prototo Desktop to get a link and a QR code. Anyone opens it in the free Prototo app on iPhone and the prototype runs natively. There is no developer account, code signing, upload or beta review.
Do I need to code?
No. Claude Code or Codex writes the code. You describe what you want and review it in the live iPhone preview.
How much does it cost?
Building locally is free and unlimited, and your first publish starts a 7-day trial. Plus is $8 a month for unlimited sharing. Team is $16 per seat a month. AI usage runs on your own Claude Code or Codex plan.
Keep reading
Download Prototo for Mac. Free to build, and viewers get the free Prototo app on iPhone.