Bookmarklets are compact JavaScript programs stored as browser bookmarks. They allow you to perform quick actions or inject scripts into webpages without needing a browser extension or dev tools.
Example JavaScript input:
alert("Hello from your bookmarklet!");
Corresponding Bookmarklet output:
javascript:alert(%22Hello%20from%20your%20bookmarklet!%22)
To use it, copy the output and create a new bookmark in your browser. Paste the generated string into the bookmark’s URL field. Clicking the bookmark will execute the JavaScript instantly on any page you're viewing.
This is perfect for debugging, automating repetitive tasks, scraping data, or injecting custom CSS/JS on-the-fly — all without installing plugins or altering the site’s codebase.