Build an app with Claude

Connect Exotool to Claude, describe the app you have in mind, and Claude builds a first version you can open on your phone within minutes: a complete progressive web app, screens, data and behaviour, with the server side included. What Claude builds is an Exotool diagram, which you can read, change in the editor, or change again by asking. The generated source is yours to run on a host of your choice.

What you need

A Claude account that can add connectors: claude.ai in the browser, or the Claude desktop app.
An Exotool account. The free plan is enough, and every plan works with Claude. The sign-in page can create the account for you if you have none.

Three steps

Connect Exotool. Open Exotool in the Claude directory and choose Connect. Or, in Claude, open Settings → Connectors → Add custom connector and paste https://mcp.ops.exotool.com/mcp.
Sign in with your Exotool account when Claude asks.
Ask. In a new chat, describe the app. To see it work at once, type Build me a simple picture database app. Claude copies a working sample into your account, compiles it, and gives you a preview address to open on your phone or computer, and the editor's address to see the diagram it made.

What to ask for

Describe the app the way you would to a colleague: who uses it, what they see, what they can do, what is stored. Some first prompts that work:

Build me an app where members of my club sign up for events and see who else is coming
Build a simple inventory app: items with a photo, a quantity and a location, and a search
Show me a list of sample projects I can start with, then Copy the retail store sample and rename it

Then change it the same way: Add a page that shows the last ten entries, Make the title blue, Require sign-in. Every save is backed up first, and Claude can undo its last change.

What happens, and what you see

Claude does not write your app's code. It edits the diagram, and Exotool's patented engine generates the app from the diagram, the same way every time: the device side, the server side, and the APIs between them. So what was built can be read in the diagram, in the Exotool editor, rather than in thousands of lines of generated code: a human-readable account of the app, there to examine and to audit. Claude tells you what it is doing at each step, and the editor shows the elements it changed.

After the first version

Keep asking. Claude can add screens, lists, forms, images, behaviour and data, upload an icon or a background, and fix build errors it caused.
Open the editor. The diagram is yours to change by hand: drag a page, edit an activity, change a template. Claude sees your changes the next time it loads the diagram.
Ship it. While you build, the app runs in Exotool's sandbox with a preview address you can share. To publish, deploy the generated source on a host of your choice, with your own database.

Limits and safety

Claude works only in your own account, on your own projects, through the connector you authorised; it can be disconnected in Claude's settings at any time. It does not create the external resources an app may use (a database account, a mail server): those are made in the editor. Server-side code it authors is shown to you before it is saved. The details are in the Help Center: the Exotool MCP server for Claude and the tool reference.

Why Exotool and Claude, rather than a code-writing AI builder

Most AI app builders let the model write the code and meter the conversation in credits or tokens. With Exotool, an engine writes the code from a design you can read, Claude is used through your own Claude account with nothing metered on Exotool's side, and the result runs wherever you want. The engine also decides what runs on the device and what on the server, so the database is reached only from the server side and the browser never holds a database key, where many builders leave that to per-row rules a model may forget. The comparisons go through this tool by tool; the MCP app builder page explains the connector itself.