When Mixel — an iPad-based collage app — launched last November, one of its features quickly caused frustration: Its requirement that users log in with Facebook before they could start creating and sharing art.

The reason for that requirement, Mixel co-founder (and former NYTimes.com design director) Khoi Vinh explained, was real names. Vinh wanted to build the Mixel community around real names, not anonymity or pseudonyms. "We think this is essential to the kind of experience we're building: a family-friendly environment that's suitable for just about anyone," he wrote.

At the time, Facebook was pretty much his only option. But that is starting to change. And as proving your online identity becomes more important, it's a valuable race for the players involved to win.

Perhaps Facebook's biggest competitor is now Google+. With 90 million users, it is still significantly smaller than Facebook, which boasts more than 800 million active users. But as Google integrates Google+ into more of its services, that number should grow. Facebook should easily beat Google+ to 1 billion users, but with Google's reach in search, mobile services like Android, and YouTube, the race to 2 billion could be closer.

Twitter, too, is a worthy competitor in the online identity race. The company famously doesn't verify real names — mainly for celebrities and brand partners — and it's hard to imagine a time when Twitter would require your real name.

But Twitter does seem to be favoring real names these days: They are now displayed by default — when available — on its website and in its official apps.

Twitter may have other reasons for that — the number of "pretty" usernames without numbers will eventually run out. But Twitter also clearly has interest in serving as an identity tool — its co-founder Jack Dorsey, also a founder of mobile payments company Square, even speaks of using your Twitter account as one way to justify your financial trustworthiness. So if Twitter can serve as a reliable source of your consistent online identity — even if it's not your official, real name — that seems valuable.

Other large companies, such as Apple, Amazon, AT&T, and Verizon, boast tens of millions of real-name accounts, many with credit cards attached to them. That is incredibly valuable to those companies, as it permits frictionless authentication and commerce for new services and devices, such as Apple's App Store and Amazon's ever-growing digital marketplace.

But with high public sensitivity over financial information and the idea of identity theft — plus the competitive advantage of keeping that data in-house — it seems unlikely that Apple, Amazon, or the others would simply open their identity services to developers. So for now, inherently "social" services like Facebook, Google+, Twitter, and LinkedIn — each with many millions of users — seem most useful as web identity-verification services.

This all begs a bigger question, though: Whether real, birth names are actually the best way to identify ourselves in an increasingly digital society.

To varying degrees, governments and financial-type companies mostly require you to have and use a name, as they have for centuries. The digital revolution, however, started within our lifetimes, and may eventually dictate new identity norms. In many online communities, anonymity — or at least the ability to use pseudonyms — is expected and sometimes demanded. If that becomes more common, who knows what offline human naming conventions will look like in a few decades.

Google, for one, recently announced an interesting new policy change for Google+: In addition to real names, it will also start allowing individuals to use consistent, established "alternate names." These range from established offline pseudonyms like Madonna to online nicknames "with a meaningful following." It still seems to prefer real names — see Google's naming policy — but there's some wiggle room now.

For now, it seems the more formal a digital community, the more your real, proper name matters — or at least a provable, consistent alternate. And as long as that's the case, the race to hold, secure, and pass along your identity will be a valuable one.

Facebook COO Sheryl Sandberg, speaking at the DLD conference in Munich this week, attributed the trend "from anonymity to authentic identity" on the Web as one of the main reasons that social media has become such an important part of daily life. "What we do online is increasingly about who we are," she said. "We are our real identities online."

You can be confident that Facebook enjoys its status as the top identity gatekeeper, and is very protective over it — it's worth a lot.

Meanwhile, Mixel — the company that got flack for its Facebook/real-name login requirement — has been integrating Google+ authentication support into its product, and it eventually plans to support the new "alternate" names feature.

"We like what Google+ is doing for alternate names — an 'authenticated' or 'established' name is good for us too," founder Khoi Vinh says.

Photo: Paulo Brandão via Flickr (cc)