That’s Mashery CEO Oren Michels‘ explanation for why his company is growing so quickly. The API management company has just hit 100,000 developers using their service, Michels says. Just about a year ago, that number stood at 35,000. And now they’ve just gotten a big new round of funding to help deal with and maintain that fast expansion.

Mashery has just closed an $11 million Series D round led by OpenView Venture Partners. Also participating were previous investors Cisco, Formative Ventures, 406 Ventures, and First Round Capital. With the funding, Scott Maxwell, senior managing director and founder of OpenView, has taken a board seat.

The new funding brings the total raised to just shy of $25 million. And while Michels declined to give the valuation, he does note that this round was at a “significant premium” over the last round (a $5.5 million one in February of last year).

So what has led to a tripling of developers using Mashery in the past year? Apps, says Michels. It has been mostly Android and iOS leading that charge, obviously. But Michels also notes that the videogame consoles are also driving quite a bit of growth recently.

He also says that Mashery’s technology is now used in some 25,000 live apps out there.

“A great app ‘grants a wish’ — so companies are going to need lots of apps to meet the needs of different groups of customers at different places, times, and use cases,” Michels says. “The only way to make that happen is to have secure, scalable, easy-to-use APIs — that can be the ingredients of the wishes,” he continues.

Cute. And apparently good business.

The round, led by Cisco, is also being participated in by existing investors, Formative Ventures, First Round Capital, and 406 Ventures. Cisco, which is a key player in networking, video, mobile, and cloud services is a good investor for Mashery to pick up as the web continues to evolve to new devices and move towards the cloud. The Cisco investment should also help open new businesses to the idea of using Mashery’s services.

“It’s been interesting to see the market for API services develop. While there are still plenty of people who can’t even spell ‘API’, we’re seeing some amazing brands not just testing the waters of innovation for the sake of innovation, but actually driving significant revenue and business growth through their API,” Mashery  CEO Oren Michels tells us. He continues, “More and more companies are seeing the power of putting their services – whether they be e-commerce, media, data, or anything else – where their customers want to interact with them rather than expecting their customers to do everything at the company’s website. Opening an API is the fastest, easiest and cheapest way to interact with users on third party platforms and mobile devices, and to enable new services that they couldn’t offer themselves. I’m really excited to see how this will grow in the next few years.”

With the new money, Mashery will expand its product as well as hire more people in sales and marketing to further cement itself in certain verticals. Currently, Mashery has over 40,000 developers connected to its network which includes clients such as Best Buy, Netflix, Reuters, the New York Times, and Trulia.

Mashery had raised $8.2 million over its previous rounds, so the new money brings that total up to $13.7 million. In the space, Mashery competes with 3scale.

Barcelona-based 3Scale Networks is launching its API management service today at the Plugg conference (which is run by TechCrunch editor Robin Wauters). With every Web startup releasing their own APIs as a matter of course these days, 3Scale offers a startups who don’t want to deal with all the hassles of managing their own APIs their own enterprise Web service that does it for them.

3Scale manages signups, tracks usage, offers user forums, stores online documentation, and handles online billing. The service runs on Amazon’s EC2, S3 ,and cloud computing Web services. 3Scale starts charging only once the billing for an API kicks in, which is usually above a certain threshold of free usage. 3Scale was previously in beta. Now companies can host their API management portal on their own sub-domain.

The startup will be competing with Mashery, which has been helping other companies manage their APIs for quite a while now. 3Scale co-founder Steven Willmott says that he is taking a more light-weight, self-serve approach, which he hopes will broaden the appeal of API management services.

An API, or Application Program Interface, is the interface that allows developers to leverage some one else’s data or functionality to create mashups. The discourse around data sharing and collaboration has largely moved beyond urging companies to offer APIs – now the task at hand is to make the offering of quality APIs easy. That’s what Mashery offers as a service.

Mashery was founded by former Feedster team members Oren Michaels, Kirsten Spoljaric, Clay Loveless and Scott Rafer. Rafer is also the CEO of MyBlogLog (our coverage). The company was incorporated in May and received under $1 million in backing in June. Investors include Josh Kopelman, Jeff Clavier, Rajeev Motwani, Ron Conway, Ariel Poler, Dave McClure, David Rose, and Scott Kurnit. Kopelman, of First Round Capital, is the lead investor and chairman.

The future is going to be built out of APIs – though still controversial in some quarters today, in time they will be as common as corporate web sites are now. Who’s going to build the series of tubes that makes such a future possible? Mashery is aiming to get into that game early.

There’s a broad spectrum of mashup infrastructure service providers already emerging. Companies like Widgetbox let consumers easily mashup data and applications into their existing websites (see also tomorrow’s SpringWidgets), Teqlo and Ning are the next step up in complexity and StrikeIron targets the enterprise market (specifically the part of it that uses the acronym SOA a lot). Mashery is aimed at companies that already recognize the importance of APIs and developer community but want to save money and time by paying some one else to set up the support infrastructure and do it right. It has a different feel to it than StrikeIron, visiting the two companies’ sites will make some differences quickly apparent.

Thankfully, Mashery emphasizes throughout their site that users own all of their own data and can easily export it at any time. That data is stored and processed with Amazon’s S3 storage and EC2 elastic compute cloud. Thus scaling up quickly and affordably will always be an option for Mashery. This is a striking example of the kind of company commoditized storage and processing in the cloud make possible.

A free account with Mashery includes a wiki to annotate API documentation, a developer’s blog and forum – all with moderation, administrative control and your company’s branding down to the CSS. It feels to me like Basecamp for APIs. A full list of free features can be found on the site.

A Pro account includes metrics to track use, developer registration, key issuance and access management. In the near term future, Pro accounts will include support for payment processing for commercial APIs.

The company says that Pro accounts for a typical API and community will cost between $10k and $20k per year. They emphasize that this cost is much lower than even a single employee managing the project and doing continuing technology development.

The first APIs that developers can connect with in Mashery are the open source business search solution Baynote and the website personalization service Loomia.

I’m not a developer myself so Mashery’s service quality and performance isn’t within my abilities to review, but I do know that this is a startup that is emblematic of the direction that the best of the web is going.

APIs changing under the feet of developers building on top of them is a significant problem and providing an easy way to annotate documentation should prove very useful to developers. Security and easy access control are two of the biggest concerns that companies considering an API consider. If Mashery can prove an effective service provider in alleviating these kinds of concerns for their customers and the development community then they are going to be a key force in the realization of a future built of mashups.