Stock Option Plans (Tables)

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement [Abstract]

Schedule of stock option activity

The following tables summarize stock option activity and related information for the three and six months ended June 30, 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 April 1, 2020	2,591,909	2,458,091	$	4.74	6.58	$	—
Options canceled	3,404	(3,404)	$	3.51
Balance at June 30, 2020	2,595,313	2,454,687	$	4.74	6.33	$	—
Exercisable at June 30, 2020		2,251,243	$	4.83	6.22	$	—
Balance at April 1, 2019	1,653,674	2,371,545	$	4.85	7.23	$	—
Options granted	(57,926)	57,926	$	3.14
Options canceled	87,031	(87,031)	$	4.01
Balance at June 30, 2019	1,682,779	2,342,440	$	4.84	7.16	$	—
Exercisable at June 30, 2019		1,865,066	$	5.00	7.01	$	—

	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	15,097	(15,097)	$	4.17
Balance at June 30, 2020	2,595,313	2,454,687	$	4.74	6.33	$	—
Exercisable at June 30, 2020		2,251,243	$	4.83	6.22	$	—
Balance at January 1, 2019	1,648,039	2,377,180	$	4.83	7.46	$	—
Options granted	(57,926)	57,926	$	3.14
Options canceled	92,666	(92,666)	$	4.34
Balance at June 30, 2019	1,682,779	2,342,440	$	4.84	7.16	$	—
Exercisable at June 30, 2019		1,865,066	$	5.00	7.01	$	—

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 June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Cost of revenue	$	11	$	10	$	26	$	20
Research and development	40		43		86		86
Sales and marketing	5		7		12		16
General and administrative	48		77		112		154
Total	$	104	$	137	$	236	$	276