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Prerequisites

Before you begin, ensure you have the following installed:
Required for running @sei-js applications:
  • Node.js (v18 or higher) - Required for npx and package management
  • nvm (Node Version Manager) - Recommended for managing Node.js versions
Verify your installation: node --version should output v18.0.0 or higher
Traditional Editors:
  • VS Code - Popular, lightweight with excellent TypeScript support
  • WebStorm - Full-featured IDE with advanced debugging and refactoring
AI-Powered Editors:
  • Cursor - VS Code fork with built-in AI coding assistance
  • Windsurf - AI-first development environment with intelligent code generation
All editors work great with @sei-js projects. Choose based on your preference for AI assistance and feature requirements.

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Create your first Sei application

1

Initialize your project

Generate a new Sei application using our CLI tool:
npx @sei-js/create-sei app
Expected outcome: A new project directory with TypeScript configuration, testing setup, and example code.
The CLI will ask you to choose a template. Select “React + Wagmi” for a full-featured web application, or “Node.js” for backend/script development.
2

Navigate and install dependencies

Move into your project directory and install dependencies:
cd app
npm install
Expected outcome: All dependencies installed successfully without errors.
Common issues and solutions:
  • Node version conflicts: Use nvm use to switch to the correct Node.js version
  • Permission errors: Avoid using sudo with npm. Use nvm or fix npm permissions
  • Network timeouts: Try switching to a different registry: npm config set registry https://registry.npmjs.org/
3

Start your development server

Launch your application in development mode:
npm run dev
Expected outcome: Development server running at http://localhost:3000 with hot reload enabled.
Your browser should automatically open to show your new Sei application with:
  • Wallet connection button
  • Network status display
  • Example interactions ready to test

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What you can build

Your new Sei application comes with examples and patterns for common blockchain interactions:

Connect Wallets

Connect to any Sei-compatible wallet including MetaMask, Compass, and more using the built-in wallet integration

Check Balances

Fetch and display wallet balances for SEI and other tokens with real-time updates

Query Blockchain Data

Access blockchain information like total SEI supply using precompile contracts

Smart Contract Interactions

Deploy and interact with smart contracts including simple examples like counters and token transfers