A startup called Heroku is launching the commercial version of its platform to help developers deploy their applications to the web. The San Francisco company already provides its “provisionless web hosting” to 23,000 developers, but now it’s ready to start making money from the service.

The idea, says co-founder and chief executive James Lindenbaum, is to eliminate all a developer’s worries about making sure they have enough computing capacity, memory, and storage. Instead, developers just build their applications, and Heroku handles the deployment. Once an application is deployed on Heroku, the company adds or subtracts “dynos” (a package with a unique copy of the application code, framework, middleware, Rack, application server, Ruby virtual machine, and POSIX environment) depending on demand.

Lindenbaum says the platform that’s closest to Heroku’s is probably the Google App Engine, but there are two key differences. For one thing, rather than supporting a swath of languages, Heroku is focused on delivering the best experience for Ruby on Rails, a framework that’s known for fast development. (App Engine currently supports Python and Java, with plans to add more languages.) Also, Heroku is open, meaning that it’s easy to move apps and data in and out of its platform, while App Engine includes a number of proprietary technologies that make that more difficult.

Heroku also uses Amazon’s Elastic Compute Cloud for its underlying infrastructure. A number of other companies, such as RightScale, are trying to help developers manage applications hosted by Amazon, but most of them are management tools that sit on top of Amazon, so a customer buys infrastructure from Amazon and then buys the software to manage it. With Heroku, developers deploy their applications to Heroku, which handles the rest; Amazon’s infrastructure is completely invisible in the process.

As for pricing, Lindenbaum says customers will pay depending on how many resources their applications use. He estimates that an enterprise customer will probably pay between $5,000 and $10,000 a month, a “Web 2.0” customer (such as a Facebook application) might pay between $2,000 and $5,000, and individual developers could pay as little as $50 a month. There’s even a free tier of services, mainly for apps that are in the early stages of development.

“If you broke it down to a per-unit cost, that’s higher than you might pay if you do it yourself, but we think there’s value to a truly elastic, scalable service,” Lindenbaum says.

Heroku raised $3 million from Redpoint Ventures and undisclosed angel investors. It was incubated by Y Combinator. Another competitor is Engine Yard.