In a really big deal for San Francisco-based Coinbase, one of the world’s leading Bitcoin wallets and merchant processing platforms, the startup is opening its doors to European customers in 13 countries.

This will be its long-awaited first foray outside of the U.S. The company is one of the biggest Bitcoin wallets in the world with 1.6 million customers, 36,000 merchants including large partners like Overstock and Wikipedia and has 6,000 developers.

But they’ve held off on expanding internationally because it’s pretty complicated from a regulatory and legal perspective. For one, many different European countries have different emerging guidelines on how to handle crypto-currencies. Plus, you need multiple bank partners, which Coinbase has secured. (They aren’t naming names though because it’s a competitive advantage.)

“A lot of the regulatory environment is still unclear. Some countries have posted guidance on it, while others have been totally silent about it,” said Coinbase CEO Brian Armstrong. “We went through a process with each of these countries. We interpreted their guidance, told regulators about our plans and our goals of what we wanted to do. We had a bit of a dialogue, and some countries got comfortable. I will say we certainly have taken a more proactive reaching out to regulators.”

The 13 countries Coinbase is adding include Italy, Spain, France, Belgium, the Netherlands, Austria, Cyprus, Finland, Greece, Latvia,Malta, Portugal, and Slovakia.

 “I think we’re probably covering roughly 60 percent of the European Union’s GDP at launch,” Armstrong said.

Any consumer in these countries should be able to buy and sell Bitcoin through Coinbase, but only up to a maximum of 500 euro per day during the beta. This will cover transactions between Bitcoin and the euro, along with authorized European bank accounts

“Cross-border payments are the real promise of Bitcoin,” Armstrong said.