Where can I install Browser Extensions?
Although majority of browsers support Extensions / Add-ons, let's focus on the most commonly used browsers in the market1.
Google Chrome
Safari
Microsoft Edge
Mozilla Firefox
Is there a Browser API Extension standard?
In 2015, a community working group was formed under the W3C to create a single standard application programming interface (API) for browser extensions. While that goal is unlikely to be achieved, the majority of browsers already use the same or very similar APIs due to the popularity of Google Chrome.
Chrome was the first browser with an extension API based solely on HTML, CSS, and JavaScript.
Edge has the same API as Chrome, extensions can be installed directly from the Chrome Web Store.
Firefox extensions are now largely compatible with their Chrome counterparts.
With the release of Safari 14 for macOS, the browser added support for Web extensions developed with the Chrome API.
How can I develop Browser Extensions?
Although all the browsers support Chrome's Extension API, we can find documentation for developing extensions for each browser in the below links:
Chrome - developer.chrome.com/docs/extensions
Safari - developer.apple.com/documentation/safariser..
Edge - developer.microsoft.com/en-us/microsoft-edg..
Firefox - extensionworkshop.com
Should I develop extensions for each browser separately?
As mentioned above, all browsers support chrome extension API, but it might have certain differences and it may not support the certain / latest manifest version(More on manifest later) if the chrome extension you have written falls under this criteria.
That said each browser provides tools for helping with the conversion from the ".crx" file to the file supported for that browser.
Safari - developer.apple.com/documentation/safariser..
Edge - As Edge is based on chromium, the same extension should work. Here are different ways to install it on the edge. groovypost.com/howto/install-extensions-on-..
Firefox - extensionworkshop.com/documentation/develop..
How can I install Browser Extensions?
Each browser has its own store where the extensions can be found and installed.
To publish in some of the stores, you may need to have a developer account which may come with associated costs.
Chrome - chrome.google.com/webstore/category/extensi..
Safari - Can be installed only from the native app store.
Edge - microsoftedge.microsoft.com/addons/Microsof..
Firefox - addons.mozilla.org/en-US/firefox/extensions