| Schedule of Quarterly Financial Information |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Three Months Ended | | | Mar. 31, 2014 | | Jun. 30, 2014 | | Sep. 30, 2014 | | Dec. 31, 2014 | | Mar. 31, 2015 | | Jun. 30, 2015 | | Sep. 30, 2015 | | Dec. 31, 2015 | | | (unaudited) | | | (in thousands, except per share data) | Revenues | | $ | 30,356 |
| | $ | 32,302 |
| | $ | 34,348 |
| | $ | 36,573 |
| | $ | 37,493 |
| | $ | 39,877 |
| | $ | 42,469 |
| | $ | 44,445 |
| Cost of revenues | | 6,846 |
| | 7,175 |
| | 7,421 |
| | 7,521 |
| | 7,964 |
| | 8,157 |
| | 8,762 |
| | 9,002 |
| Gross profit | | 23,510 |
| | 25,127 |
| | 26,927 |
| | 29,052 |
| | 29,529 |
| | 31,720 |
| | 33,707 |
| | 35,443 |
| Operating expenses: | | | | | | | | | | | | | | | | | Research and development | | 6,404 |
| | 6,411 |
| | 6,490 |
| | 7,015 |
| | 7,150 |
| | 7,205 |
| | 7,564 |
| | 7,532 |
| Sales and marketing | | 12,492 |
| | 11,845 |
| | 11,774 |
| | 11,938 |
| | 11,443 |
| | 12,776 |
| | 12,282 |
| | 13,068 |
| General and administrative | | 4,875 |
| | 5,081 |
| | 5,156 |
| | 5,888 |
| | 6,016 |
| | 6,427 |
| | 6,983 |
| | 7,147 |
| Total operating expenses | | 23,771 |
| | 23,337 |
| | 23,420 |
| | 24,841 |
| | 24,609 |
| | 26,408 |
| | 26,829 |
| | 27,747 |
| Income (loss) from operations | | (261 | ) | | 1,790 |
| | 3,507 |
| | 4,211 |
| | 4,920 |
| | 5,312 |
| | 6,878 |
| | 7,696 |
| Other income (expense), net | | 12 |
| | 41 |
| | (119 | ) | | (568 | ) | | (77 | ) | | 128 |
| | (154 | ) | | (183 | ) | Income (loss) before income taxes | | (249 | ) | | 1,831 |
| | 3,388 |
| | 3,643 |
| | 4,843 |
| | 5,440 |
| | 6,724 |
| | 7,513 |
| Provision for (benefit from) income taxes(1) | | 182 |
| | 174 |
| | 283 |
| | (22,270 | ) | | 1,841 |
| | 2,124 |
| | 2,601 |
| | 2,089 |
| Net income (loss) | | $ | (431 | ) | | $ | 1,657 |
| | $ | 3,105 |
| | $ | 25,913 |
| | $ | 3,002 |
| | $ | 3,316 |
| | $ | 4,123 |
| | $ | 5,424 |
| Net income (loss) per share: | | | | | | | | | | | | | | | | | Basic | | $ | (0.01 | ) | | $ | 0.05 |
| | $ | 0.09 |
| | $ | 0.77 |
| | $ | 0.09 |
| | $ | 0.10 |
| | $ | 0.12 |
| | $ | 0.16 |
| Diluted | | $ | (0.01 | ) | | $ | 0.04 |
| | $ | 0.08 |
| | $ | 0.69 |
| | $ | 0.08 |
| | $ | 0.09 |
| | $ | 0.11 |
| | $ | 0.14 |
|
(1) Provision for income taxes consists primarily of taxes on income in foreign jurisdictions and state income taxes in the U.S. In the fourth quarter of 2014, the Company recorded a tax benefit of $23.7 million to recognize its U.S. federal and certain state deferred tax assets. |