I made this in order to avoid using the slow and/or poorly optimized sharing buttons from AddThis or ShareThis. It provides sharing buttons for four of the major social websites (Twitter, Facebook, Google+ and StumbleUpon) in inline SVG and CSS — not a lick of Javascript.
Simply cut and paste the CSS into your existing CSS file and the HTML into your web page! This code adds absolutely zero HTTP requests to your site and only weighs 6k in the standard version. That means a faster website.
You can see this code in action on the Multiplex website. (I’m using different opacity levels for the rollover states, but it’s essentially the same.)
This code is in the public domain. Do what you want with it; I don't care. I didn't design the icons; I just turned them into SVG. The SVG was optimized with Peter Collingridge's Javascript SVG Editor and then edited to add the rollover and mousedown states.
This entry on Stack Overflow should help you customize the sharing links as needed.
UPDATED 7/16/13: I’ve added an alternate HTML file using base64-encoded PNG fallbacks for those of you who care to support janky browsers that don’t like inline SVG. While regular PNG images would work fine, using base64-encoded PNGs avoids the additional HTTP request(s) they would generate, even in browsers using the SVG versions.
Web Coder Tools’ Online image to base64 converter was used to encode the PNG fallbacks.
— Gordon McAlpin
UPDATE (8/15/13): I’ve adjusted the markup slightly to address bugs with older IE versions, specifically removing the XML namespace attribute and separating the closing tag from self-closing SVG elements (per Stuntbox’s “Making Inline SVG Play Nice in Legacy IE” post).
I’ve also moved the opacity to the CSS on all versions, because I found that having multiple instances of the share_icons on one page would conflict with each other (this was probably because of the id tag, but it also cuts down the size of the [non-cacheable] inline code a little more).