Capitalized software development costs, exclusive of those recorded within property and equipment, consisted of the following:

	March 31, 2020			December 31, 2019
	(in thousands)
Gross capitalized software development costs	$	67,074		$	61,641
Accumulated amortization		(48,248	)		(44,848	)
Capitalized software development costs, net	$	18,826		$	16,793

These capitalized software development costs are associated with software developed for customer purchase. Capitalized software development costs recorded within property and equipment are associated with software developed for Company use.

Capitalized software development costs are amortized on a straight-line basis over their estimated useful life of two years.

The following table summarizes software development costs capitalized, stock-based compensation included in capitalized software development costs, and amortization of capitalized software development costs.

	Three Months Ended March 31,
	2020		2019
	(in thousands)
Software development costs capitalized	$	5,433	$	3,278
Stock-based compensation included in capitalized software development costs	$	838	$	508
Amortization of capitalized software development costs	$	3,475	$	2,495