Yahoo serves cocktails from its back-end (Photo: aoife mac/Flickr)

Google, Amazon, and Yahoo began life as websites, but they’ve evolved into something more. Now, they share their underlying infrastructure with the outside world, letting other businesses take advantage of the complex hardware and software systems they’ve erected over the years.

Google lets outsiders run applications atop its infrastructure via Google App Engine. Amazon offers its Elastic Compute Cloud (EC2). And sometime next year, Yahoo will launch “Manhattan” — an online service where anyone can build and host applications using standard web technologies such as HTML5 and JavaScript.

Unveiled on Wednesday morning, Manhattan is designed to facilitate the creation of digital magazines and other consumer applications that can be used across a wide variety of devices, from desktops and notebooks to iPads and Android phones.

“We thought about building really cool apps for the iPhone or iPad. But what happens when Android really starts taking off? What happens on web browsers? What happens on feature phones?” Bruno Fernandez-Ruiz, Yahoo vice president, fellow, and chief platform architect, tells Wired.

“So we’ve built a number of things that let you build an application for the Apple App Store, but also distribute the same code to mobile web browsers and browsers on the desktop.”

On Wednesday, Yahoo launched a virtual newsstand atop its site — dubbed Livestand — and Manhattan will provide a means of building digital publications for this service. But developers will also have the freedom to run their apps wherever they like. The only restriction is that applications must be built with standard web technologies.

Early next year, before the arrival of Manhattan, Yahoo will open-source a programming platform dubbed “Mojito.” Based on a widely used open source project known as Node.js, Mojito will allow developers to build entire applications with JavaScript, the web’s standard scripting language. Typically, JavaScript is used to build an application’s front end — the bit that runs on the user’s device — but with Node.js and Mojito, you can also use JavaScript on the back end — the bit that runs on the server.

This also means that Mojito applications can run on devices that are not equipped to run JavaScript. If you’re using a feature phone, for instance, you can still use a Mojito application because the same code can be run on the server side. Yahoo call it Mojito because these application are both “modules” (self-contained application that include everything they need to run on their own) and “widgets” (small applications with an interface designed for quick and easy interaction). “From modules and widgets, we came to ‘mojits,” Fernandez-Ruiz says. “And this became Mojito.”

This, in turn, gave rise to the cocktail theme. Mojito was joined by Manhattan.

You can run these applications on your own servers. But when Manhattan arrives — sometime in 2012 — you’ll also have the option of running them on Yahoo’s infrastructure. This not only frees you from running your own machines; it lets you tap into various other services Yahoo has built for its own site. This includes Yahoo’s CORE technology, which can personalize content for individual users or groups of users, and Yahoo’s ad serving platform.

Unlike Amazon’s EC2 — an “infrastructure cloud” — Manhattan is what’s known as a “platform cloud.” So rather than merely providing raw servers and storage, it provides a higher-level software platform that hides the underlying infrastructure. In this sense, it’s akin to Google App Engine. But whereas App Engine lets you build more complex applications using sophisticated languages like Python and Java, Manhattan handles only HTML5, Javascript, and other standard web tools.

Yahoo is targeting a simpler breed of application. But it’s also working to boost the influence of the web. “Like other web players, we have a fear that the web browser will become obsolete,” says Fernandez-Ruiz. “But by pushing the right standards and making the right tools open source, we think we can solve this problem.”