Stock Option Plans (Tables)

3 Months Ended

Mar. 31, 2020

Share-based Payment Arrangement [Abstract]

Schedule of stock option activity

The following table summarizes stock option activity and related information for the three months ended March 31, 2020 and 2019:

	Number of Shares Available for Grant	Number of Options Outstanding	Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Term (in Years)	Aggregate Intrinsic Value
Balance at January 1, 2020	1,550,628	2,473,130	$	4.67	6.84	$	—
Options authorized	1,029,588	—	$	—
Options exercised	—	(3,346)	$	3.76
Options canceled	11,693	(11,693)	$	4.37
Balance at March 31, 2020	2,591,909	2,458,091	$	4.74	6.58	$	—
Exercisable at March 31, 2020		2,160,101	$	4.86	6.44	$	—
Balance at January 1, 2019	1,648,039	2,377,180	$	4.83	7.46	$	—
Options canceled	5,635	(5,635)	$	5.29
Balance at March 31, 2019	1,653,674	2,371,545	$	4.85	7.23	$	—
Exercisable at March 31, 2019		1,834,360	$	5.00	7.09	$	—

Stock-based compensation expense

The accompanying condensed consolidated statement of operations and comprehensive loss includes stock-based compensation expense as follows (in thousands):

	Three Months Ended March 31,
	2020		2019
Cost of revenue	$	15	$	10
Research and development	46		43
Sales and marketing	7		9
General and administrative	64		77
Total	$	132	$	139