Talk about starting your year off on the right foot.

Two days ago, Codecademy — a startup that’s looking to bring programming to the masses — launched a nifty initiative called Code Year. It’s pretty straightforward: sign up, and each week you’ll receive some programming lessons in your email inbox.

And apparently, there are a lot of people who want to learn how to code. Code Year just had its 100,000th user sign up — a remarkable milestone given that the site has only been up for 48 hours. And that number continues to grow at a rapid pace.

Codecademy cofounder Zach Sims says that the growth is being driven by a huge amount of sharing on both Facebook and Twitter. Users are able to Tweet and ‘Like’ the page both before they sign up, and immediately after they’ve entered their information. It also helps that the entire signup process takes all of five seconds — you simply need to enter your email address.

Given the viral nature of the site, I asked Sims for a breakdown on which services were contributing the most to its growth. The clear leader? Twitter.

Sims says that t.co links (which are using Twitter’s official URL shortener) have generated 33.59% of the site’s traffic. Facebook clocks in at 16.18%. And Google+ drove a much more modest 2.37% (Update: As pointed out in the comments, there actually was no button for sharing the site to Google+, so people had to manually share it — that 2.37% isn’t half bad).

Also worth noting: freelance designer Sacha Greif has detailed the process that went into the site’s landing page, which has obviously been extremely effective. His post outlines the selection of the site’s font, its icon (a calendar, instead of the initially-considered lightbulb), and the block quotes. But most impressive is the amount of time it took: one hour.

Sims says that the startup wants Code Year to be more than just a New Year’s resolution — they’re working with other companies to promote programming literacy.