How to test your web app on an iPhone with an AI agent
Disclosure: I make thumbs, one of the options below. I'll say where each option fits, including where mine doesn't.
Your web app looks right in Chrome's device mode. Then someone opens it in Safari on an iPhone and the keyboard covers the Submit button, a small field zooms the page, or a fixed footer sits under the browser bar. DevTools emulation shows the viewport size; it doesn't show Safari on iOS.
An AI agent can do the checking if it can see a phone's screen and tap it. Here's how that works today.
What the agent needs
Three things: see the screen (a screenshot plus what's tappable), act (tap, type, swipe, scroll, open a link) and read back what happened. Anything that gives an agent those on an iPhone or the iOS Simulator will do.
Four ways to do it
| Option | Good for | Catch |
|---|---|---|
| Xcode's Simulator + a local MCP server (for example open-source servers that drive the iOS Simulator) | Free, runs on your Mac, you control everything | Needs a Mac with Xcode, and you set it up yourself |
| Appium + WebDriverAgent | Full control, real devices, CI | Real engineering to set up and maintain; you write the scripts rather than the agent |
| A device cloud (BrowserStack and similar) | Many devices and OS versions | Built for test suites; check whether it exposes an agent-friendly interface |
| A remote MCP server with a phone behind it (thumbs) | Nothing to install: add one URL to Claude Code and sign in | Early access only, on the iOS Simulator: Safari and Apple's apps, shared between testers. A real iPhone of your own is planned, with no date or price yet |
If you already have Xcode and enjoy the setup, a local Simulator MCP server is a fine choice. If you don't want a Mac in the loop, a remote one is easier.
Step by step with Claude Code and thumbs
- Join the waitlist. Early access is free and people are let in one at a time.
- When you get the email, run:
claude mcp add --transport http thumbs https://mcp.usethumbs.com/mcp - In Claude Code, run
/mcpand sign in with Google. In the Claude app, add the same URL as a custom connector. - Ask for the check.
Prompts that work
- "Open https://your-site.com/signup in Safari and tell me if the keyboard hides the Submit button."
- "Open the pricing page, scroll to the bottom and tell me if anything is cut off or overlaps."
- "Tap the email field. Does the page zoom? Describe what happened and send the screenshot."
- "Open our checkout link and tell me every field the keyboard covers."
Each time the agent gets a screenshot and a numbered list of the elements it can tap, so it can say "tap 4" rather than guess pixel positions.
What it can't tell you
- It's the iOS Simulator in early access. Safari in the Simulator is a good guide to layout and behaviour, but it isn't a real device: no real touch hardware, no real network or battery conditions.
- It doesn't replace your test suite. It's good for a quick "does this look and work right on a phone?" before a release.
- Banking apps, Apple Pay and anything behind Face ID don't work.
- The simulator is shared between testers, so don't sign into personal accounts on it.
FAQ
Can an AI agent test a website on an iPhone? Yes, if it can see the screen and tap it, for example through an MCP server that drives Safari on a phone or simulator.
Do I need a Mac? Not with a remote option: you add a URL and sign in. With a local Simulator MCP server, yes.
Is it a real iPhone? In thumbs' early access it's the iOS Simulator. A real iPhone of your own is planned; it isn't available yet and has no date or price.
Does it work with Claude Code? Yes: claude mcp add --transport http thumbs https://mcp.usethumbs.com/mcp, then /mcp to sign in.
Is it free? Early access is free. The own-iPhone option isn't available yet and has no price; you'd see any price before paying anything.
Keep reading
- iOS Simulator MCP: local or remote, and which to use.
- How to test an iOS app with Claude Code or Cursor.
- How to give an AI agent an iPhone with MCP: how it works under the hood, local versus remote, Simulator versus a real iPhone.
- What thumbs can do today, and the questions people ask.
- Does the iOS keyboard cover your Submit button?: the keyboard check in depth.
- A mobile-web QA checklist for an AI agent: ten checks to run before a release.