A little-known startup that has quietly amassed 100,000 Wall Street users just scored a big investment

• OpenFin, a startup that helps electronic trading firms build their desktop applications, has raised $15 million in funding
• Backers include JPMorgan, high-speed trading firm DRW, and VC firm Euclid Opportunities
• The firm wants to become what iOS and Android is to the mobile application world

You might have heard of high-speed market maker Citadel Securities, or interdealer broker Tullett Prebon Icap. Then there is TruMid, the bond trading platform backed by George Soros and Peter Thiel, and Treasury trading startup OpenDoor.

Well, there's one little-known firm that connects them all, and many more Wall Street trading firms, behind the scenes: OpenFin. Now, the startup, which helps electronic trading firms build their desktop applications, is getting its own moment in the spotlight.

The firm has raised $15 million in a Series B fundraising round from investors including JPMorgan, fintech backer Euclid Opportunities and high-speed trading firm DRW. Bain Capital Ventures, Pivot Investment Partners and Nyca Partners have already invested in the firm, as have the likes of Chris Conde, former CEO of Sungard, and Tom Glocer, former CEO of Thomson Reuters.

The vision, according to CEO Mazy Dar, a former chief strategy officer at Creditex, is to become to Wall Street what iOS and Android is to the mobile application world.

"When you have the iOS layer, and Android, that is the layer that enables developers to know what they are building their app in," Dar said. That's what OpenFin is aiming to become.

The firm already has 35 investment banks and trading firms signed up, according to Dar, and powers applications licensed on over 100,000 desktops. He said the firm has been growing revenue 100% year-over-year for the past few years, and is close to being cash flow positive. The $15 million investment will enable the firm to expand, with Dar planning to double headcount from 25 in New York and London currently to 50 in 12 months time.

The aim is to become "the industry wide operating layer," he said. Right now, OpenFin is typically delivered to a desktop together with an application that runs on it. The hope is that, in time, OpenFin will be on the desktop independent of any application, becoming a kind of finance application ecosystem all of its own.

"OpenFin enabled us to reach hundreds of client desktops instantly with an operating layer already vetted by many major banks and financial institutions," Tony Schiavo, chief technology officer at Trumid, said.

There are three key pillars to this strategy. First, having apps that can be downloaded and updated with ease, the same way you would download an app on your phone, and then have it update regularly.

Then there is the layer of security, a key issue for any Wall Street institution. Finally, there is interoperability, or letting the apps talk to one another, the same way social media apps connect on your phone.

"We're in a world where apps are siloed, and by and large do not talk to one another," Dar said. "The human sitting in front of the six monitors is the integration layer. With OpenFin, they are now able to talk to one another, share data and contacts."