Happo

December 16, 2025 · View on GitHub

An open source library for integrating with happo.io - a visual and accessibility regression testing platform that helps you catch unintended changes in your applications.

📚 Documentation

For comprehensive documentation, visit docs.happo.io.

🚀 Features

CLI Tool: Includes a command-line interface for easy integration
Flexible Configuration: Support for multiple configuration file formats
TypeScript Support: Built with TypeScript and provides full type definitions
ES Modules: Uses modern ES modules for better tree-shaking and performance

📦 Installation

npm install happo --save-dev
# or
pnpm add happo --save-dev
# or
yarn add happo --dev

🛠️ Usage

Basic Configuration

Create a happo.config.ts file in your project root:

import { defineConfig } from 'happo';

export default defineConfig({
  apiKey: process.env.HAPPO_API_KEY!,
  apiSecret: process.env.HAPPO_API_SECRET!,
  targets: {
    'chrome-desktop': {
      type: 'chrome',
      viewport: '1280x720',
    },
    'firefox-desktop': {
      type: 'firefox',
      viewport: '1280x720',
    },
    'ios-safari': {
      type: 'ios-safari',
    },
  },
});

CLI Usage

Run Happo using the CLI:

npx happo

The CLI will automatically find your configuration file and run the visual regression test suite.

🔧 Configuration Options

Supported Configuration Files

The library automatically detects configuration files in the following order:

happo.config.js
happo.config.mjs
happo.config.cjs
happo.config.ts
happo.config.mts
happo.config.cts

Key Configuration Properties

apiKey & apiSecret: Authentication credentials for happo.io
integration: Set up the integration type
targets: Target configurations, including regular browsers and accessibility targets
project: Optional project name