Next month, Grindr, the gay and bisexual mobile networking service, will celebrate its second birthday.

By that time, the iPhone and BlackBerry app will have been downloaded some 1.65 million times. At the time of my interview with CEO and founder Joel Simkhai, the Grindr community is growing by 100,000 downloads a month and has more than 300,000 daily users spread over 180 countries. Grindr’s success is even more impressive when you consider it began on less than $5,000.

“We just thought this would be a cool app,” Joel tells me. “As a gay man I thought: wouldn’t it be great if I could walk into any room or go to a new city and see who’s gay? Did we think it would become a business? Or that it would impact as much as it has? We had no idea.”

Before founding Grindr, Joel, 34, held a number of jobs after leaving Massachusetts’ Tufts University with a degree in economics and international relations. None of them were for him.

“I come from a family of entrepreneurs. I always wanted to work for myself. I didn’t like the notion of joining a company and slowly having to work my way up. One day I thought about what else I might do and started selling magazines on eBay.”

Selling magazines on eBay eventually turned into an online subscription business which, while not ultimately successful, taught Joel a lot about how to build and manage a business. What it didn’t do was satisfy his broader interest in technology.

Despite lacking the programming skills typical of technology entrepreneurs, Joel claims he had the notion for location-based social networking many years before the technology became available. It was that dream that led him to approach the founders of Dodgeball, an early developer of location-based networking using SMS. Joel’s idea was to licence their technology and focus it on the gay community.

“It was 2004. They said thanks, but no thanks. They were just two guys and they had their hands full. Looking back though, I’m not sure if the Dodgeball technology would have worked for us.”

Four years later, the technology Joel had been looking for came to market in a big way. Steve Jobs, Apple’s CEO, gave his keynote speech in June 2008 unveiling the second-generation iPhone, which now contained GPS technology. Joel watched the speech on a QuickTime stream from Apple’s website.

“I knew this was it. This is what I’d been waiting for. It took me two months from Jobs’ announcement to find a developer to write the software I needed. I didn’t have much money, but I had a dream. He loved the idea and agreed to work for me in his spare time.”

While the software was being written, Joel and friend Scott Lewallen came up with Grindr’s name and logo.

“We knew the logo had to be unique, memorable and above all masculine. We looked at tribal art from Africa and Polynesia and we kept seeing masks. That was our inspiration. We thought about grinding people together sort of like a coffee grinder.”

Grindr became available for download in March 2009, just nine months after Jobs’ presentation.

“And then nothing much happened,” Joel confesses. “We didn’t really have a marketing plan so in the beginning it was just me, Scott and our friends with the app on our phones. Then we hit on the idea of holding parties. Jeffrey Sanker, the promoter of Palm Springs’ White Party, was a friend of Scott’s, he loved Grindr and he gave us a booth at his party. More than 5,000 guys attended and for the first time you could see the app’s potential: when you logged on more than 50 guys showed up.

“After that we started going to all the Pride marches and using guerrilla marketing. Come June we were in San Francisco when someone came and told me Stephen Fry had just mentioned Grindr on a TV show called Top Gear.”

Britain’s most famous technophile did more than just mention Grindr on Top Gear: he hijacked the BBC motoring programme, with an estimated global audience of 350 million viewers, for a minute and a half as he explained Grindr’s intricacies to host Jeremy Clarkson and tried to find another Grindr user in the studio audience.

“The impact was instant,” says Joel. “We had about 10,000 downloads overnight, increasing our base by 50 per cent. Within a week we were up to 40,000. Someone once asked me if we paid Stephen Fry to mention us, but we didn’t. Apparently one of the guys he works with is gay and showed it to him the week of his appearance.”

Fry’s exploits go some way in explaining why London ranks ahead of New York, Los Angeles and San Francisco in terms of Grindr users, but the app has primarily taken off through word of mouth the efforts of volunteers who bought into the “wouldn’t it be great if” idea.

“With Grindr you can find your future partner at a bus stop or at a supermarket,” he says. “It’s a new world of possibility.”

Can Grindr really be used to find a boyfriend or is it just for guys looking for sex?

“I think Grindr reflects real life,” Joel answers. “At the end of the day the application can only reflect its users. There are guys out there looking for love and there are those looking for sex. Often that can be the same guy, just at different times in his life or day.”

Does he have any advice for Grindr users when it comes to personal safety or practicing safe sex?

“Be as careful as you would be in real life, both in terms of meeting new people and in staying healthy. As a company we employ moderators to monitor content, but Grindr users are no more vetted than the ones you meet in bars or clubs. Do we encourage promiscuity? Not at all, the platform we provide is neutral in that sense. We simply make it easier to meet people, be that for friendship, dating or otherwise. We’ve even had a Grindr user get help to fix his broken down car using our app.”

Given Grindr’s inexorable rise I end by asking Joel what he plans to do next.

“We’d like to bring what we have to the rest of the world. We’d like to help lesbian women and straight men and women. I think we’d see different usage patterns, but I think we’re all looking for easier ways to meet new people. Facebook helps you keep in touch with your friends, but it doesn’t necessarily help you make new ones. That’s what we’re working on.”