Responsively App is a free, open-source browser designed to simplify responsive website development and testing. It displays websites simultaneously across multiple device-sized viewports. Developers can inspect how layouts behave on smartphones, tablets, and desktop screens without switching browser windows. User interactions are mirrored across all active previews to streamline testing. The application includes more than 30 device profiles and supports custom viewport configurations. Its integrated developer tools provide element inspection and debugging capabilities. Users can capture screenshots across devices and preview changes through hot reloading. Built with Electron for Windows, macOS, and Linux, Responsively App also provides an MCP server for AI-assisted browser testing. Its releases repository distributes compiled application binaries.
Features
- Simultaneous responsive website previews across multiple device screen sizes
- Mirrored scrolling, clicking, and typing across synchronized browser viewports
- Over 30 predefined device profiles with customizable screen dimensions
- Unified developer tools for inspecting and debugging responsive page elements
- One-click multi-device screenshots with hot reloading during development
- MCP server integration for AI-assisted navigation, interaction, and visual testing