Andres Wolberg-Stok was promoted about a year ago to global mobile and tablet banking director at Citigroup. "It's a bigger field in which to inflict damage," he jokes.

So far this year, he's traveled to Singapore, Mexico, London and Brussels. "It keeps us true to the old motto, the Citi never sleeps. Having a global team in with members in the US, Europe and Asia is extraordinary because the sun never sets on the team, people are always working. You can get a lot done."

His new mission: to create one code base from which mobile apps will be delivered to the $1.95 trillion-asset New York bank's three dozen consumer markets around the world.

"The whole drive we're on is to leverage our globality as a financial institution, which is pretty unique," Wolberg-Stok says. "There's huge scope to leverage investments in app design and development and a single code base to serve all markets where each one of those markets, even the U.S., would not be able to make that sort of investment" on its own.

There are local clearinghouses, laws, currencies, languages and social mores to deal with in each country. But, Wolberg-Stok points out, Citi already has online and mobile banking systems in each of those countries that plug into local infrastructures and can cope with local regulations.

"It's hard to build a bank from zero in each country, but once you have a bank operating there, it's not that hard to come with a global mobile app and website and plug that into our local Citi systems," he says. Language, currency, and payments differences require only marginal changes, he says. Videos and images are localized.

The global tablet app, Citi for iPad, has already gone live in Russia and Hong Kong.

"When we operate in another country, we compete not just with other would-be global banks, we compete with the best local banks," he observes.

Language translations are handled by staff and vendors. "The trick is in building your global code base in such a way that it's easy to swap out the phrases and replace the language," he says.

Replicating upgrades around the world becomes faster, easier and cheaper when you have the same code base everywhere," Wolberg-Stok says. "If you have a different code base in each country, someone could have the best idea in the world, you'd never be able to implement it in all the markets because you'd have to reinvent the wheel every time."

Citi developers built this new platform internally using HTML5, basing it on the bank's U.S. iPad app. An app wrapper is downloaded at Apple's App Store. It's the bank's first foray into HTML5.

HTML5 gets mixed reviews in the industry. "Every time a major company goes with HTML 5 or not with HTML5, half the audience points a finger and says, 'Ah, you see!' The reality is it depends on your industry and line of business and whether you're constantly pushing things onto users or it's more of a pull model." One of the benefits of HTML5 for Citi is that changes can be made remotely; users don't have to download new versions of the app.

The user experience is "very smooth and very liquid almost at the app level," Wolberg-Stok says.

Later this year, the HTML5 "app" will be rolled out in the U.S.