Web browser bookmarklets allow you to perform actions on the current page with just a click or tap. They’re a lightweight alternative to browser extensions. They even work on mobile browsers that don’t support traditional extensions.

To use bookmarklets, all you need is a web browser that supports bookmarks — that’s it!

Bookmarklets Explained

Web pages you view in your browser use JavaScript code. That’s why web pages aren’t just static documents anymore — they’re dynamic. A bookmarklet is a normal bookmark with a piece of JavaScript code instead of a web address. When you click or tap the bookmarklet, it will execute the JavaScript code on the current page instead of loading a different page, as most bookmarks do.

Bookmarklets can be used to do something to a web page with a single click. For example, you’ll find bookmarklets associated with web services like Twitter, Facebook, Google+, LinkedIn, Pocket, and LastPass. When you click the bookmarklet, it will run code that lets you easily share the current page with that service.

Bookmarklets don’t just have to be  associated with web services. A bookmarklet you click could modify the appearance of the page, stripping away most of the junk and giving you a clean “reading mode.” It could alter fonts, remove images, or insert other content. It can access anything the web page could access. For example, you could use a bookmarklet to reveal a password that just appears as ******* on the page.

Unlike browser extensions, bookmarklets don’t run in the background and bog down your browser. They don’t do anything at all until you click them.

Because they just use the standard bookmark system, they can also be used in mobile browsers where you couldn’t run extensions. For example, you could install the Pocket bookmarklet in Safari on an iPad and get an “Add to Pocket” option in Safari. Safari doesn’t offer browsing extensions and Apple’s iOS doesn’t offer a “Share” feature like Android and Windows 8 do, so this is the only way to get this direct integration. You could even use the LastPass bookmarklets in Safari on an iPad to integrate LastPass with the Safari web browser.

Where to Find Bookmarklets

If you’re looking for a bookmarklet for a particular service, you’ll generally find the bookmarklet on that service’s site. Websites like Twitter, Facebook, and Pocket host pages where they provide bookmarklets along with browser extensions.

Bookmarklets aren’t like programs. They’re really just a piece of text that you can put in a bookmarklet, so you don’t have to download them a specific site. You can get them from practically anywhere — installing them just involves copying a bit of text off of a web page.

For example, you can just search the web for “reveal password bookmarklet” if you wanted a bookmarklet that will reveal passwords. We’ve covered many of the must-have bookmarklets — and our readers have chimed in too — so take a look at our lists for more examples.

How to Install a Bookmarklet

Bookmarklets are simple to install. When you hover over a bookmarklet on a web page, you’ll see its address begins with “javascript:”.

If you have your web browser’s bookmark or favorites toolbar visible, the easiest way to install a bookmarklet is with drag-and-drop. Press Ctrl+Shift+B to show your bookmarks toolbar if you’re using Chrome or Internet Explorer. In Firefox, right-click the toolbar and click Bookmarks Toolbar.

Just drag and drop this link to your bookmark toolbar. The bookmarklet is now installed.

You can also install bookmarklets manually. Select the bookmarklet’s code and copy it to your clipboard. If the bookmarklet is a link, right-click or long-press the link and copy its address to your clipboard.

Open your browser’s bookmarks manager, add a bookmark, and paste the JavaScript code directly into the address box. Give your bookmarklet a name and save it.

How to Use a Bookmarklet

Bookmarklets are easiest to use if you have your browser’s bookmarks toolbar enabled. Just click the bookmarklet and your browser will run it on the current page.

If you don’t have a bookmarks toolbar — such as on Safari on an iPad or another mobile browser — just open your browser’s bookmarks pane and tap or click the bookmark.

In mobile Chrome, you’ll need to launch the bookmarklet from the location bar. Open the web page you want to run the bookmarklet on, tap your location bar, and start searching for the name of the bookmarklet. Tap the bookmarklet’s name to run it on the current page.

Note that the bookmarklet only appears here because we have it saved as a bookmark in Chrome. You’ll need to add the bookmarklet to your browser’s bookmarks before you can use it in this way.

The location bar approach may also be necessary in other browsers. The trick is loading the bookmark so that it will be associated with your current tab. You can’t just open your bookmarks in a separate browser tab and run the bookmarklet from there — it will run on that other browser tab.

Bookmarklets are powerful and flexible. While they’re not as flashy as browser extensions, they’re much more lightweight and allow you to get extension-like features in more limited mobile browsers.