Free Manifest.json Generator – Create PWA & Chrome Extension Manifests Online

The manifest.json file is the foundation of any Progressive Web App (PWA) or browser extension. It tells the browser everything it needs to know: the app name, icons, start URL, display mode, theme color, background color, and scope. Writing this file manually from memory is tedious and error-prone. Our free Manifest.json Generator makes it fast, accurate, and completely painless. A Progressive Web App is a web application that can be installed on a user's device like a native app, works offline via service workers, and provides an app-like experience in the browser. The manifest.json is what enables this installability—without it, browsers cannot offer the 'Add to Home Screen' prompt, and the app cannot appear in the device's app launcher. For Chrome extensions, the manifest.json (specifically Manifest V3, the current required format) defines the extension's permissions, background scripts, content scripts, action icons, and metadata that the Chrome Web Store uses for listing display. Our generator supports both PWA manifest format and Chrome Extension Manifest V3, making it a versatile utility for web developers and extension developers alike.

Key Fields in a PWA manifest.json Explained

Understanding what each manifest field does helps you configure your app correctly. The name field is the full application name displayed when installed. The short_name is displayed on device home screens and app launchers where space is limited—keep it under 12 characters. The start_url specifies the page that loads when the user launches the installed PWA; set it to your app's main route, such as / or /app. The display field controls how the PWA chrome is shown: standalone removes the browser address bar for an app-like feel, fullscreen hides all browser UI, browser shows the app in a standard browser tab, and minimal-ui shows minimal browser controls. Most production PWAs use standalone. The theme_color sets the color of the browser toolbar and status bar, while background_color determines the splash screen color shown during app loading—both should match your brand palette. The icons array is critical: you need icon sizes at 192×192 and 512×512 pixels (PNG format) for basic PWA compliance. Google's Lighthouse audit requires at least a 512px icon for a passing PWA score. Our generator validates your icon configurations and helps you structure the icons array correctly.

Generating a Chrome Extension Manifest V3 File

Chrome Extension development requires a manifest.json that conforms to Manifest Version 3 (MV3), the format required by the Chrome Web Store since 2023. MV3 introduced significant changes from V2, including the replacement of background pages with service workers, the new declarativeNetRequest API for network interception, and stricter content security policies. Our generator helps you configure the essential MV3 fields: manifest_version (must be 3), name, version, description, permissions (a curated list of available Chrome APIs), host_permissions (URLs your extension can access), action (formerly browser_action), and icons in the required sizes (16, 32, 48, 128 pixels). For extensions with content scripts, the generator adds the content_scripts array with the appropriate matches patterns and script file references. For extensions using a background service worker, it adds the background.service_worker field. The output is a complete, Chrome Web Store-compliant manifest that you can drop directly into your extension project directory.

How Manifest.json Affects PWA Lighthouse Scores and App Store Listings

Google's Lighthouse audit tool—built into Chrome DevTools—scores PWAs on multiple criteria, with manifest configuration being a key component of the 'PWA' category score. A properly configured manifest.json contributes to achieving a passing Lighthouse PWA audit, which in turn can affect your app's visibility in Google Search results and its eligibility for web-based app store listings. Specific manifest fields Lighthouse checks include: the presence of a start_url, a display value of standalone or fullscreen, icons at 192px and 512px with the correct purpose field values, and a theme_color that matches your application. Missing any of these causes Lighthouse to flag your PWA as non-installable. For Chrome extensions listed on the Chrome Web Store, a well-formed manifest is equally critical. The store uses manifest fields to populate your listing: the name and description come directly from your manifest, and icons in the correct sizes determine your extension's visual identity in the Chrome Web Store search results. Our generator ensures all required fields are present and correctly formatted before you submit.

Browser-Based Manifest Generator – No Installation, Complete Privacy

Your project configuration files, including the manifest.json, can contain sensitive information such as internal app names, OAuth client IDs, and extension permissions that reveal your security architecture. Our DevForge Manifest.json Generator processes all inputs client-side in your browser—nothing is transmitted to external servers. This means you can safely generate manifests for internal tools, enterprise dashboards, or pre-launch applications without exposing your project details. The tool is completely free, with no account required and no usage limits. It works in all modern browsers on desktop and mobile devices. After generating your manifest, the tool provides a one-click download option to save the file as manifest.json, ready to drop into your project root. Alternatively, use the copy button to paste the JSON directly into your code editor. Use our generator every time you start a new PWA or browser extension project to build your manifest correctly from day one.