Sizzy

About Sizzy

Sizzy is a Chromium-based browser built for web development, designed to display a website on multiple device viewports simultaneously in one window rather than requiring separate browser windows. It synchronizes scrolling, clicks, and form input across all displayed devices in real time, and simulates real device dimensions, pixel ratios, and user agents, accounting for browser and OS UI to reflect actual screen heights. The device list is updated regularly to include new releases.

Beyond layout testing, it includes a unified DevTools panel covering all devices at once, a visual CSS debugging tool, a network request inspector for REST, GraphQL, and form calls, and network condition simulation (slow 3G, flaky WiFi, offline). A session manager allows logging into different user accounts on different devices at the same time to test role-based permissions, with configurations savable as presets. Other features include project-based workspaces for bookmarks, notes, and snippets, locale switching for internationalization testing, a "Photo Studio" mode for arranging devices on a free canvas with custom backgrounds for mockups and screenshots, and screenshot/video/GIF capture and recording history.

Sizzy is aimed at web developers and teams building and testing responsive interfaces, including those needing to verify layouts and permissions across multiple pages and user roles. It offers a 14-day free trial with no credit card required, and paid plans starting at $12/month billed annually.

Key features

• View and test multiple device breakpoints side-by-side in one window
• Synchronize scrolling, clicks, and form input across all devices in real-time
• Universal DevTools with unified console, debug styles, API inspector, and network simulation
• Photo Studio mode for creating device mockups with custom backgrounds
• Multi-account session manager for testing different user roles simultaneously
• Built on Chromium, so Chrome extensions work

Frequently asked questions