Bookmarklets: simple plugins for your browser

A bookmarklet is a bookmark whose URL (web address) contains a small program that does something useful with the currently displayed web page. To execute the program, you click on the bookmark.

• Installation: Usually, a bookmarklet is provided on the web as a link that you drag to your bookmarks bar.
• Examples of useful bookmarklets:
  • This blog lists several bookmarklets.
  • Twitter: share the current web page on Twitter.
  • Tumblr: publish a link to the current web page.
  • Instapaper: archive a copy of the current web page. (There is major magic going on behind the scenes.)
• Tip: bookmarklets can be quickly invoked via browser keywords.

A simple example would be the following program inside a URL.

javascript:alert("hello")

You can click on the link to execute it, you can also add the link to your bookmarks bar.

Update 2011-06-08: Implementing bookmarklets in JavaScript