STATEMENTS OF OPERATIONS - USD ($)
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
STATEMENTS OF OPERATIONS      
Revenue $ 32,496,548 $ 31,593,720 $ 15,653,057
Cost of revenue 6,154,836 5,840,407 3,404,400
Gross profit 26,341,712 25,753,313 12,248,657
Operating expenses:      
General and administrative 8,795,703 7,769,881 4,816,973
Sales and marketing 5,278,448 4,705,977 3,297,120
Research and development 1,347,507 1,764,306 1,068,674
Total operating expenses 15,421,658 14,240,164 9,182,767
Income from operations 10,920,054 11,513,149 3,065,890
Other income (expense), net 32,680 121,385 (48,549)
Income before provision for income taxes 10,952,734 11,634,534 3,017,341
Provision for income taxes 3,738,189 4,104,614 966,975
Net income $ 7,214,545 $ 7,529,920 $ 2,050,366
Net income per share:      
Basic (in dollars per share) $ 0.67 $ 0.68 $ 0.23
Diluted (in dollars per share) $ 0.60 $ 0.60 $ 0.20
Weighted-average shares outstanding:      
Basic (in shares) 10,818,427 11,003,272 8,743,461
Diluted (in shares) 11,989,681 12,556,887 10,219,143