Mobile accounted for more than 50% of ecommerce last year, yet was just 0.08% of Broadway sales. TodayTix is changing that with its last-minute theater ticket app, and it’s making good money along the way. Six months after launch, the startup has 120,000 users, 15 employees, is making a hefty 12% margin on purchases, and is set to sell 1% to 2% of all Broadway tickets in 2014. The theater market might seem small, but at $13 billion a year, it’s actually bigger than movie box office sales in the US. Internationally, it's a $50 billion market that’s hardly evolved since the dawn of the web. Now TodayTix wants to bring the dusty business of plays, musicals, circus, and more into the mobile age. Merritt Baer is the man to do it. I knew him from Stanford where he double majored in drama and economics. Baer was the big man on campus when it came to theater, directing the Spring musicals and serving on the board of theater society. After graduating he spent three years as the head of theater ticket inventory at Viagogo, an online ticket marketplace. He then started his own theater production company and won a Tony award for producing the resurrection of Death Of A Salesman with Philip Seymour Hoffman in 2012. His background in ticketing technology and theater accolades give TodayTix street cred in the industry and helped it forge relationships with the top Broadway venues. Baer tells me “The experience of buying tickets hasn’t evolved." Getting last-minute Broadway tickets means you probably either stood in line through the crowds and elements at the TKTS booth in Time Square, or juggled screens in clunky online interfaces trying to find a deal. TodayTix reimagines this flow with its simple iOS and Android apps for buying tickets up to a week in advance. It lists every Broadway show with tickets available in a colorful, information rich feed, plus offers the deepest publicly available discounts. You can quickly pick from the available dates and times, see seating charts, and choose your section and price point. This might sound familiar from the concert space where there's WillCall, YPlan, Applauze, and more, but there's still a big opportunity in building a dedicated app for theater. TodayTix charges a flat $5 convenience fee per ticket, which is lower than what you’ll find on Ticketmaster or Telecharge, which add around $8 to $15 per seat. If you pick your tickets up from the box office, TodayTix collects a small commission from the theater. Alternatively, you can choose the ritzy concierge pickup option for $5 extra, where a TodayTix representative will be waiting outside your theater in a red coat for a quick hand-off and expedited entry in case you’re short on time or patience. I tried the concierge buying experience while I was in NYC for TechCrunch Disrupt in May. We showed up late, but instead of having to worry that the box office might have closed or been mad, I found the TodayTix rep down the street. They gave me the tickets with a smile and we made it inside without missing much of the show. It’s still a bit tough to compare tickets for different shows or dates on TodayTix. Since theater shows run most days of the week, sometimes twice a day, it can be hard to know whether you should spend more for a night show, or could get better seats for the same price at a matinee. That’s a problem with almost all theater ticket buying interfaces, but it’d be great to see TodayTix add a comparison shopping feature. Even with its current system, it poses a threat to TKTS, Broadway.com, Ticketmaster, Telecharge, and other sellers. They might have SEO, but TodayTix is the first result when you search "Broadway" on the App Store. Its sales are growing 40% per month, 40% of its 120,000 users are active each month, and 40% of sales come from repeat customers. That level of retention means once people switch to buying theater tickets with the app, they stick with it, and could provide high lifetime values. Though you can find solid discounts on TodayTix, Baer says about 50% of purchases in the app are for full-price tickets since people end up wanting nicer seats. It's also using a Dropbox-style growth model, giving people in-app credit for inviting their friends. While it’s currently only in New York City, TodayTix is preparing to launch in London’s West End this year, and has eyes on Chicago and Las Vegas. Eventually, it wants to sell for every venue in the world. To fuel that growth, it raised a $550,000 seed round last spring and a $1 million convertible note at the start of 2014. With each new market, people will have more reason to download and remember the app. TodayTix is also working with mobile deep link retargeting advertising system URX and others to hit people with ticket offers or re-engagement reminders when they visit the cities where it operates. TodayTix faces an stodgy market and established players with deep pockets,  but the shift to mobile is on its side. By focusing on the last-minute piece of the ticket pie, the app has more flexibility to offer a streamlined buying experience, "the same way as HotelTonight" says Baer. That's music to the ears of TodayTix's customers, and drama for its competitors.