Intangible assets

12 Months Ended

Mar. 31, 2022

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible assets

Intangible assets

Intangible assets comprise the following (in thousands):

		As of March 31, 2021						As of March 31, 2022
	Useful life (in years)	Gross Carrying amount		Accumulated amortization		Net		Gross Carrying amount		Accumulated amortization		Net
Patents and trademarks	3 - 20	$	115	$	(82)	$	33	$	105	$	(70)	$	35
Customer relationships	2 - 15	2,687		(2,271)		416		2,772		(2,528)		244
Internal-use software, technology and other	1 - 18	35,618		(17,764)		17,854		42,335		(22,154)		20,181
Total		$	38,420	$	(20,117)	$	18,303	$	45,212	$	(24,752)	$	20,460

For the years ended March 31, 2020, 2021 and 2022, amortization expense of $3.8 million, $3.7 million, and $4.3 million has been recognized, respectively.

The weighted average amortization period of intangible assets purchased during the year ended March 31, 2021 and 2022 is 1 year and 5 years, respectively.

As of March 31, 2021 and 2022, there was internal-use software in progress of $3.8 million, and $5.5 million, respectively.

As of March 31, 2022, the estimated future amortization expense is as follows (in thousands):

Years ending March 31,
2023	$	8,115
2024	4,767
2025	4,124
2026	2,521
2027	650
Thereafter	283
Total	$	20,460