Amazon Web Services (AWS) and its rivals have created a lot of publicity around serverless computing, but Iron.io was talking about it first, and now the startup wants to spread the feature to every cloud.

It's an effort, launched in February, that the company has been calling Project Kratos, and it reached general availability yesterday.

The term “serverless” annoys lots of people in the cloud world because, of course, the computing has to be run on a server somewhere. But traditionally, cloud customers have rented an entire server at a time. “Serverless” refers to the idea of renting just a portion of a server, sharing that CPU with other cloud customers. In other words, you can run functions in the cloud without having to care what kind of server they're running on.

AWS calls this service Lambda. Microsoft Azure and Google Cloud Platform both call it Functions. Iron.io's founders prefer to think of it as the idea they came up with years ago.

“We love those guys, because four years ago, there was no market, and customers didn't know what to call it,” says Chad Arimura, Iron.io's CEO and one of its founders.

Lambda and its rivals are all proprietary; you can't move a Lambda job over to Azure, for instance. Project Kratos is all about removing that lock-in.

“The architects of the Fortune 2000, they want a multicloud strategy,” Arimura says.

Iron.io houses the serverless functions inside Docker containers, which will run in just about any cloud or in on-premises data centers. The service would also work with offerings such as Azure Stack, Microsoft's private-cloud version of Azure. “In fact, we've been talking to their partner teams about including Iron.io in their stack,” Arimura says.

So, what would you use “serverless” for? Here's an example: When AWS announced Lambda in 2014, the company described it as a good way to run overnight batch jobs. A customer could schedule a job to run later, and Lambda would automatically grab the computing resources it needed, possibly spreading the job among multiple servers.

Iron.io was founded in 2011 by Arimura and Travis Reeder (now CTO). They were consultants, running a shop doing coding for hire. The platform that they built for their own developers, one that let them work on multiple clients' projects using the same resources in the cloud, became the basis for Iron.io, which they founded in 2011.

As it turned out, Iron.io's platform had been multicloud from the beginning, because while Arimura and Reeder were using AWS, some of their customers were running infrastructure on Rackspace.

Iron.io now has 45 employees and about 400 customers, including large enterprises, Arimura says.