curl/docs/cmdline-opts/parallel-max.md

c	SPDX-License-Identifier	Long	Arg	Help	Added	Category	Multi	Scope	See-also	Example
Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.	curl	parallel-max	<num>	Maximum concurrency for parallel transfers	7.66.0	connection curl	single	global	parallel	--parallel-max 100 -Z $URL ftp://example.com/

--parallel-max

When asked to do parallel transfers, using --parallel, this option controls the maximum amount of transfers to do simultaneously.

The default is 50. 300 is the largest supported value.