FORTUNE — When Julia Steen parked in a church pew next to Kevin Hartz at a Santa Barbara wedding in 2003, Hartz decided he just had to talk to the fetching, young blonde.

“She was a mature 23-year-old, and I was an immature 33-year-old,” Kevin says dryly.

“I was a hot mess,” Julia disputes. “I didn’t even have the thing I was supposed to be reading for the wedding.”

During the reception, he stole a tray of cocktails, and sauntered over to impress Julia, an MTV executive at the time, who was talking to her coworkers. “I remember thinking, ‘This guy has cajones!'” she recalls.

It’s fair to say they both do. Ten years, one marriage in, and two daughters later, the Hartzs now run Eventbrite, the biggest ticketing company this side of Ticketmaster. Kevin serves as CEO; Julia as President. With the help of 229 employees, they have sold over 100 million tickets in 179 countries to events like South by Southwest after-parties and Bay Area marathons. (Eventbrite profits by charging a small fee for each ticket purchase.)

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Last month, the San Francisco startup crossed $1.5 billion in ticket sales, and sales are accelerating: One-third of its total ticket sales were processed over the last nine months alone. Backers like Sequoia Capital, Tiger Global Management, Khosla Ventures partner Keith Rabois, and Ron Conway have chipped in a reported $80 million to date.

When we think of Silicon Valley successes, we often view them as an overnight phenomenon, the result of a lot of luck. Neither was the case for Eventbrite. For Kevin, it was his third startup; his first, an Internet service manager for hotel chains, got acquired for $10 million just 10 months after it launched. And as a former angel investor, his bets include some smart choices: PayPal, Pinterest, and Airbnb, to name a few. Meanwhile, Julia cut her teeth in Hollywood for several years, managing shows like FX’s The Shield, Nip/Tuck, and yes, MTV’s Jackass.

So when Kevin dreamed up the idea that event ticketing could and should be done better online, it wasn’t luck. Before Eventbrite, an easy, widely-accepted online ticketing solution for individuals and smaller organizations didn’t exist. Tickemaster catered to the big names, not the startup that wanted to hold an office-warming or the mother who wanted to throw a baptism party. Eventbrite provides that.

“It’s a marketplace that truly democratizes event management and marketing, giving every organizer the tools to sell tickets and reach audiences that until recently were only available to the largest venues and organizations,” explains Sean Moriarty, an Eventbrite board member and ex-Ticketmaster CEO.

“Kevin has always consistently been ahead of his time, spotting things before they’re cool,” agrees Rabois. “Most of these people hosting long-term events needed a higher-quality product for ticketing for payments.”

Indeed, via daily emails to Rabois, Kevin convinced his friend to invest $50,000 in a little-known startup called Pinterest during its early days.

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Now, the Hartzs want to expand Eventbrite’s end-to-end experience and do so internationally, such that users use it for every step of the ticketing process, from event discovery on their mobile devices and desktops, to getting through the door to the event of their choosing. Last year, they launched “At the door,” a credit card reader that turns iPads into ticketing terminals, giving indie event promoters another way to take payments.

Given Eventbrite’s push, it seems inevitable the company, a veritable David, should take on its Goliath — Ticketmaster — but Kevin is in no rush. “People ask us all the time, ‘Why aren’t you going after them?’ That’s a very competitive, vicious ticketing space, and we’ll get there in due time. But these markets are so much more … attractive.”