How to Build an App with Claude

Artifacts

Create small interactive apps inside a Claude chat and preview them instantly. Best for tools, calculators, and prototypes.

Claude Design

Create interactive prototypes and mockups from a prompt, then hand them to Claude Code.

Claude Code

Build a real app in a project folder on your computer or in the cloud. Included in all paid plans.

Prototype in chat. Build for real in Claude Code.

• Who is the app for?
• What problem does it solve?
• What do people do today instead?
• What is the one most important action?
• How will you know it works?

An app that solves one problem well beats an app that solves ten badly.

Ask Claude to help you write a one-page spec:

• Users and their goals
• Core features for version one
• Features for later
• Screens and what each shows
• Data the app stores
• Sign-in needs
• What is out of scope

Interview me about this app idea one question at a time, then write a one-page spec with a clear version one scope.

Use artifacts or Claude Design to click through the main flow before building.

• Test the main screens
• Check the most important action takes few steps
• Show it to two or three real users
• Change the spec based on feedback

Changes are cheapest before the real code exists.

Ask Claude to recommend a stack for your skill level and app type, and to explain why.

Web app

A popular framework with good documentation

Mobile app

A cross-platform framework if you need iOS and Android

Data

A hosted database with built-in sign-in, if you need accounts

Hosting

A platform that deploys from your Git repository

Choose popular, well-documented tools. Claude knows them better and help is easier to find.

curl -fsSL https://claude.ai/install.sh | bash

Create a project folder, run claude inside it, and switch to Opus 5.5 for complex work:

/model opus /effort high

Prefer not to use the terminal? The Claude desktop app includes Claude Code in its Code tab.

Run /init to create a CLAUDE.md file, then add:

• What the app does
• The tech stack
• How to run, test, and build
• Code style rules
• Things Claude must ask before doing

Claude reads it at the start of every session.

Build one feature at a time:

• Ask for a plan first
• Approve the plan
• Let Claude build the feature
• Run the app and try it yourself
• Commit to Git when it works
• Move to the next feature

Small, tested steps beat one giant prompt.

Ask Claude to set up Git and commit after each working step. If something breaks, you can always return to the last good version.

• Store only the data you need
• Use a proven sign-in service instead of building your own
• Keep secrets in environment variables, never in code
• Set database access rules so users only see their own data
• Back up important data

• Ask Claude to write automated tests for core features
• Run the tests after every change
• Click through the app yourself
• Test on a phone
• Try wrong inputs on purpose
• Ask a friend to use it without help

When something breaks, give Claude:

• What you did
• What you expected
• What happened
• The exact error message
• A screenshot if it is visual

Ask Claude to find the root cause before changing code.

Prompt:

Review this app for security problems: exposed secrets, missing access checks, unsafe inputs, and data that should not be public. List issues by severity and fix them one at a time with my approval.

For apps handling payments, health, or sensitive personal data, get a human expert review too.

• Choose a hosting platform
• Set environment variables there, not in code
• Connect your domain
• Test the live version
• Set up error monitoring

Ask Claude to walk you through each step for your chosen platform.

• Collect feedback
• Watch where people get stuck
• Fix the biggest problem first
• Add features only when users need them

Problem

Define one clear problem.

Spec

Write version one scope.

Prototype

Click through before building.

Build

One feature at a time.

Test

Automated and by hand.

Secure

Review before launch.

Ship

Deploy and monitor.

Improve

Learn from real users.

Act as my senior developer and teacher. I want to build [app] for [users] that solves [problem]. First, interview me and write a one-page spec with a small version one. Wait for approval. Then recommend a simple, well-documented stack and explain why. Build one feature at a time: plan, build, write tests, run them, and explain what you did in plain language. Commit after each working step. Never put secrets in code, and ask before deleting anything or deploying.