Job board operator Simply Hired reported 30 percent of its job search traffic came from mobile devices, and it expects this number to rise to 50 percent by the end of 2015. Usage is expected to spread across platforms and job categories.

“Recent research estimates that only 20 to 30 percent of Fortune 500 companies currently offer mobile-friendly career sites and portals,” said Simply Hired President and CEO James Beriker. “Recruiters must figure out how to serve the mobile user or risk losing out on a massive pool of candidates.”

The most active category for mobile job search was office and administrative, with 14 percent of clicks from mobile, followed by healthcare practitioners with 13 percent of clicks from mobile.

Mobile candidates are not just killing time or “snacking” on opportunities, but more engaged than the average desktop candidate when it comes to spending time with job listings, according to the Simply Hired.

Mobile users click on 60 percent more job postings and spend 27 percent longer looking at those jobs. They also spend 25 percent more time on the site and view 25 percent more jobs.

The data is based on job seeker activity on simplyhired.com and was collected between Aug. 1 and Aug. 30.