SilverBullet is a web application. You access it via any modern browser, and it leverages a lot of recent technological advances built into modern browsers, such as service workers (for offline capabilities), IndexedDB (for storing and querying data) and cryptography APIs.
Because it is a browser-based web application, you can access it from any device with a modern web browser, this includes desktops, laptops, phones and tablets.
While it’s a browser-based web application, many browsers (such as Chromium-based and Safari-based ones) allow you to install it as a PWA, giving it an icon on your home screen, or icon in your dock, and removing any unnecessary browser Chrome, making it visually indistinguishable from a “native” desktop app:
