Responsively App: A Multi-Device Browser for Responsive Web Development

What Problem It Solves and Who It Is For

Responsively App solves the chore of manually resizing a browser window or toggling device emulation in DevTools to check how a site looks at different breakpoints. The README describes it as a modified browser built using Electron that helps in responsive web development. The target user is a web developer who needs to verify layouts across many devices and wants to do it in one place. The tool is not for testing actual device performance or real mobile browsers; it is a development aid for visual and interaction checks. The README claims it can make you '5x faster', but that is a marketing claim, not a measured benchmark. The core value is the ability to see multiple viewports at once and interact with all of them through mirrored interactions.

How It Works: Mirrored Interactions and Device Profiles

The central mechanism is mirrored user-interactions across all devices. When you click, scroll, or type in one preview pane, the same interaction is replicated in every other device preview. This is different from resizing a single viewport because you see the effect of a single gesture across all breakpoints simultaneously. The app includes 30+ built-in device profiles, and you can add custom devices. The preview layout is customizable, so you can arrange the device panes to suit your workflow. There is also a single elements inspector that works across all devices, meaning you can inspect the DOM or styles once and see how they apply to each viewport. The README does not specify the underlying rendering engine, but since it is Electron, it is likely Chromium. That means the rendering is consistent with Chrome, which is useful for most web development, but it does not emulate Safari or Firefox engines.

Getting It Running: Installation Commands

Installation is straightforward on all major platforms. For macOS, you can use Homebrew: `brew install --cask responsively`. Windows users can use Chocolatey with `choco install responsively` or winget with `winget install ResponsivelyApp`. Linux users on RPM-based distributions can install via `sudo rpm -i https://github.com/responsively-org/responsively-app/releases/download/v[VERSION]/Responsively-App-[VERSION].x86_64.rpm`, where [VERSION] is a specific release tag. Otherwise, you can download an AppImage from the releases page. The README also mentions a browser extension for Chrome, Firefox, and Edge that sends links from your regular browser to the app for instant preview. The extension is called Responsively Helper. The app itself is free to download from responsively.app. There is no mention of a command-line interface or a headless mode, so the tool is purely a GUI application.

Key Features: One-Click Screenshots and Hot Reloading

Two features stand out in the README. First, one-click screenshots on all your devices. This lets you capture a full-page screenshot of every device profile at once, which is useful for documentation or visual regression checks. Second, hot reloading is supported for developers. This means that when you edit your source code, the previews update automatically. The README does not specify which build tools or dev servers are compatible, so you may need to experiment. The elements inspector is another highlight: it works across all devices, so you can inspect an element and see its computed styles in each viewport. That is more efficient than switching between DevTools instances. These features are practical for daily development, but the README does not provide details on how to configure the preview layout or how custom devices are defined. The release notes for v1.18.0 mention a design mockup overlap feature, which suggests you can overlay a mockup on the preview, but the README does not explain it.

Limitations and Failure Modes

The most obvious limitation is that it is an Electron app, so it is a separate browser. That means it does not share cookies, sessions, or extensions with your main browser unless you use the helper extension. The mirrored interactions are a convenience, but they are not a substitute for real device testing. Touch events, viewport meta tag handling, and mobile-specific APIs may behave differently in an Electron window compared to an actual mobile browser. The README does not mention any network throttling or device emulation for performance testing, so it is the wrong tool for checking mobile network conditions. Another failure mode is that the app may struggle with sites that detect the browser environment and serve different content, since the user agent is that of Electron, not a mobile device. The README also does not specify whether the custom device profiles allow you to set user agents or viewport dimensions beyond width and height. If you need to test a specific device like an iPhone with a particular Safari version, this app will not give you that.

Alternatives and the Difference in Approach

The most direct alternative is the built-in device emulation in Chrome DevTools or Firefox Developer Tools. That approach uses a single browser window and lets you switch between device profiles, but you can only see one viewport at a time. Responsively App's key difference is simultaneous multi-viewport preview with mirrored interactions. Another alternative is a tool like BrowserStack or Sauce Labs, which provide real device clouds for testing on actual hardware. Those services run on remote infrastructure and give you true device rendering, but they are paid and have a different interaction model: you drive a single remote browser, not multiple synchronized panes. There are also standalone tools like Polypane, which is a commercial browser with a similar multi-pane approach, but it is not open source. The open-source nature of Responsively App is a differentiator, but you must accept the AGPL-3.0 license. That license has implications if you distribute a modified version, but the application itself is free to use.

Maintenance, Upgrade Cost, and License

The repository is active, with the last push on 2026-02-17 and a recent release v1.18.0. The release cadence is roughly every few months, with v1.18.0 in February 2026, v1.17.1 in October 2025, and v1.17.0 in August 2025. That suggests ongoing maintenance, but the README does not provide a changelog or upgrade instructions beyond downloading new releases. The upgrade cost is low for end users: you download a new binary or use the package manager to update. For developers who want to build from source, the CONTRIBUTING.md guide is referenced, but the README does not detail the build process. The license is AGPL-3.0, which is a strong copyleft license. If you modify the app and distribute it, you must make your modifications available under the same license. This is fine for internal use, but if you plan to embed or extend the app in a commercial product, you need to consult a lawyer. The README does not mention any paid tiers or enterprise features, so the project appears to be fully open source.

Editorial conclusion

Adopt Responsively App if you are a web developer who regularly tests responsive layouts and wants a single tool to see and interact with multiple viewports at once. It is especially useful for quick visual checks and one-click screenshots. Skip it if you need precise emulation of mobile browsers, deep network throttling, or if your team relies on a single-browser workflow. Before adopting, verify that the AGPL-3.0 license fits your distribution model, and test the hot reloading with your build tool, since the README does not specify which bundlers or dev servers are supported. Also confirm that the browser extension works with your primary browser, as the helper extension is a key part of the workflow.

Official sources

1. Official documentation
2. Official README
3. Project repository
4. Release notes