The average big company will spend about 14% of its overall marketing budget this year on industry conferences and customer events targeted at business buyers. While that’s less than last year, it’s more than for any other activity, including the 10% allocated for digital advertising. Separate research estimates the annual total devoted to these activities (as of 2012) at a whopping $565 billion.

The way that money is spent, however, is definitely evolving. More than half of the roughly 1,100 marketers surveyed in late 2014 by Forrester Research are investing in “digital enhancements,” including mobile applications that guide an attendee’s experience before, during and after an event.

Notes Forrester analyst Laura Ramos:

These applications provide not only personalized agendas, speaker profiles, and session locators but also interactive capabilities that let attendees share profiles, take polls, give feedback and take part in promotions. Or through the use of location technology like iBeacon, they can guide attendees to sessions or exhibitors of interest.

Naturally, there’s a slew of emerging tech companies that would love for their software to be the conference app download of choice.

Among them is San Francisco-based DoubleDutch, which Wednesday disclosed a $45 million round of growth financing led by KKR. Existing investors Bessemer Venture Partners and Index Ventures also participated.

The four-year-old company sells apps event organizers use to organize schedules, manage polls, and facilitate networking. It previously raised slightly less than $38 million, according to CrunchBase. Some of its 1,000 customers include tech giant Cisco, insurance company Humana, Kimpton Hotels & Restaurants, and drug-store chain Rite Aid. It employs 260-plus people.

“We are growing north of 100% year over year and see no signs of things slowing down,” said DoubleDutch co-founder Pankaj Prasad, who is also global head of sales.

Rival Cvent, founded 1999 and based in Tysons Corner, Va., likewise reported better-than-expected revenue of $47.3 million for its second quarter although the 1,740-person company is running at a loss.

Cvent added “hundreds of customers” to its 14,000-plus-company account list, including Fortune 500 insurer Pacific Life. Other big clients include pharmaceutical giant Baxter, rental car company Enterprise, and hospitality powerhouse Marriott. For the year, Cvent expects revenue of $185 million to $186 million.

Cvent founder and CEO Reggie Aggarwal said mobile event apps streamline processes such as registration, which enables companies to devote more resources toward nurturing relationships and collecting feedback. “If I meet you physically, you feel compelled to respond. The power of events will increase over time. An event is an intense social media experience,” Aggarwal said.

Indeed, social referrals are the focus of a platform update from Bizzabo, a New York-based tech company that also sells an event platform and mobile apps. Attendees can earn discounts or refunds off their own registration when they convince friends or colleagues to sign up. “It encourages word of mouth and event buzz and is fully aligned with how the best event marketers promote their events,” said Bizzabo co-founder and CMO Alon Alroy, in a statement.

Personally, I love the concept of an app where I can coordinate my plan of attack for conferences. One thing that needs more work, however, is integration with existing calendaring and messaging tools. The apps I’ve used so far force me to recreate my schedule in two places and that won’t go over well with busy professionals.

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UPDATED, Aug. 14: Cvent’s customer count was modified, based on additional information from the company.