How MuleSoft founder Ross Mason turned free software into a $1.5 billion company

You know how startups are always going on and on about how they are going to "disrupt the legacy" vendors, those older, giant multi-billion dollar companies?

As we predicted, for hot San Francisco startup MuleSoft, that's what's actually happening. And investors continue to throw money at the company.

MuleSoft just raised a new $128 million investment, at a $1.5 billion valuation, founder Ross Mason tells us. The round was lead by Salesforce's investment arm, Salesforce Ventures. Total raised to date is $259 million.

This validation is sweet success for Mason. This company started as a small project in 2003 when he and his wife were living on the island of Malta. He was working as a corporate IT developer, struggling to make applications talk to each other, and complaining about it, until his wife told him to stop complaining and do something.

Big corporations like Tibco and Informatica charged a lot of money to big enterprise clients for products to make that easier. So Ross wrote a project called MuleSoft to connect apps, data and devices. (In geek speak, MuleSoft helps different application programming interfaces work together.) And he gave it away for free.

As the project grew, it became a business. MuleSoft offers the software as a paid cloud service. He spent four years commuting from Malta to San Francisco, where some of his employees and early investors were.

In 2010, he was on a plane (as he always was) and he was caught in the ash from the Iceland volcano Eyjafjallajökull. It was terrifying. He decided to stop the crazy commute and move to San Francisco.

And MuleSoft has been going gangbusters ever since.

Earlier investors included rivals Salesforce and SAP. And now Salesforce has doubled down with help from a slew of other VC firms like NEA, Lightspeed Venture, Hummer Winblad.

Meanwhile, both Tibco and Informatica have ceased to be public companies, going private in leveraged buy-out deals.

MuleSoft, which is likely marching toward an eventual IPO, is now doing the bubble 2.0 thing and taking gobs of VC money to stay in growth mode, postponing an IPO until its even bigger. MuleSoft will use the money to hire people, build out its product, expand its reach internationally.

The free and open source project is still there and hugely popular on GitHub. But so is MuleSoft's cloud service, which is on track to bring in $100 million, Mason tells us, having grown 2015 Q1 revenues 110% year over year, he says.

The company employs 500 people and has over 700 customers.

And Mason has given up commuting for good. About 10 months ago, he bought a house in San Francisco.