instantpwa
Help centre

Answer

What is the Window Controls Overlay API?

Short answer

The Window Controls Overlay API lets an installed desktop PWA reclaim the title-bar area next to the window’s minimize, maximize and close buttons, so the app can render its own tabs, search bar or menu there instead of leaving it blank — similar to how VS Code’s desktop app uses its title bar. It is enabled via "display_override": ["window-controls-overlay"] in the manifest.

By InstantPWA engineering·Reviewed July 25, 2026

How it is enabled

Add "window-controls-overlay" to the manifest’s display_override array; CSS env() variables report the overlay’s exact geometry so you can lay out content around the system buttons.

Support

Chromium desktop browsers (Chrome, Edge) only; no support on macOS Safari, Firefox or mobile.

Typical use case

Productivity apps that want a native-feeling custom title bar with app-specific controls instead of wasted blank space.

Sources

Related
What is a Web App Manifest?
A Web App Manifest is a JSON file — usually manifest.webmanifest — that declares your app’s name, icons, start URL, theme colour and display mode. Browsers read it to decide whether to offer the install prompt and what icon and name to show on the home screen.
Do PWAs work on Windows?
Yes. On Windows, installing a PWA through Chrome or Edge adds it to the Start menu and taskbar, gives it its own window without browser chrome, and lists it in Windows Settings → Apps alongside native applications, where it can be uninstalled the same way. Microsoft also historically indexed some PWAs directly into the Microsoft Store via PWABuilder.
Can a PWA be the default handler for a file type?
Yes, on desktop Chromium browsers. The File Handling API lets an installed PWA declare file_handlers in its manifest, associating file extensions or MIME types with the app so double-clicking a matching file (or right-clicking → Open With) launches the PWA with that file passed in via the launchQueue. This is not supported on iOS or Firefox.
Can a PWA register a custom URL protocol?
Yes. An installed PWA can register itself as the handler for a custom URL scheme (prefixed with "web+", e.g. web+myapp://) using the manifest’s protocol_handlers field, so clicking such a link anywhere on the OS opens the PWA with that URL — the same mechanism native apps use for schemes like mailto: or spotify:. It is supported on Chromium browsers; not on iOS Safari.
How many users actually install PWAs?
There is no single industry-wide install rate — it depends heavily on the product, audience and how the install prompt is presented. What is well documented is that several large companies (Twitter/X with Twitter Lite, Starbucks, Pinterest, Uber) have published PWA case studies reporting improved engagement, load times or conversion after launch, which is why PWAs remain a common choice for content and commerce sites.