SeatGeek is announcing a deal to acquire TopTix for $56 million.

While SeatGeek has made acquisitions before, this is its biggest, and the company funded the deal by raising a $57 million Series D led by Glynn Capital. (Previous investors Accel, Causeway Media Partners, Haystack Partners, Mousse Partners and Technology Crossover Ventures also participated.)

“We really weren’t thinking money,” SeatGeek’s Jack Groetzinger told me. (He’s pictured above with his co-founder, Russell d’Souza.) “We were in a pretty strong position, with cash on the balance sheet, but it felt like [this acquisition] was too good to pass up.”

He suggested that SeatGeek and TopTix make for a particularly good match because while his company has focused on building the best consumer experience for finding events and buying tickets, TopTix works on the back end, creating the tools that allow venues to accept tickets — in fact, TopTix currently processes 80 million tickets a year for customers, including the Royal Dutch Football Association, Buckingham Palace and the Ravinia Festival.

TopTix customers will become SeatGeek customers, and TopTix co-founder Eli Dagan will continue to lead the company’s engineering team in Israel.

“By marrying those two things together, we’re creating a very powerful full stack that’s miles ahead of the legacy ticketing companies,” Groetzinger said.

SeatGeek and TopTix were already working together on the launch of SeatGeek Open, a platform allowing sports teams and venues to sell tickets directly, so the acquisition is supposed to help the company expand Open more aggressively. (SeatGeek, which launched at the TechCrunch50 conference, previously focused on resale tickets.) Supposedly, the Open platform helped its first customer, Major League Soccer team Sporting Kansas City, increase online sales by 61 percent from the previous season.

While working with TopTix on the Sporting Kansas City deal, Groetzinger said he got a good look at the technology, and he liked what he saw.

“Usually when you get under-the-hood with something like this, you uncover unpleasantness,” he said. “This was quite the opposite — we were even more impressed.”