Capitalized software development costs consisted of the following (in thousands):

				As of June 30, 2019
	Gross carrying amount		Amortization period	Accumulated amortization			Net carrying amount
Capitalized software development costs	$	45,832	3 years	$	(31,982	)	$	13,850
Total capitalized software development costs	$	45,832		$	(31,982	)	$	13,850

				As of December 31, 2018
	Gross carrying amount		Amortization period	Accumulated amortization			Net carrying amount
Capitalized software development costs	$	45,677	3 years	$	(32,784	)	$	12,893
Total capitalized software development costs	$	45,677		$	(32,784	)	$	12,893

The Company capitalized software development costs of $4.3 million and $4.2 million for the six months ended June 30, 2019 and June 30, 2018, respectively.

Amortization expense for capitalized software development costs was $1.8 million and $1.4 million for the three months ended June 30, 2019 and 2018, respectively. Amortization expense for capitalized software development was $3.3 million and $2.8 million for the six months ended June 30, 2019 and 2018, respectively. Amortization of capitalized software development costs is classified within cost of revenue in the consolidated statements of operations.

The expected amortization of capitalized software development costs, as of June 30, 2019, for each of the following years is as follows (in thousands):

	Amounts
2019 (for the remaining six months)	$	3,514
2020		4,398
2021		3,915
2022		2,023
	$	13,850