Sometimes, I want to link to some online character or NPC generators. However, I know that some of the online resources, especially spell lists, are actually copyright violations.
Are these online generators ok? Here is an example.
There's nothing inherently wrong with recommending a tool. Keep in mind, though, that link-only answers are bad: you should be explaining in your answer post why the sort of resource you recommend is the best solution, such that a future reader who found your link had rotted would still know what they're looking for and why.
That generator's creating characters for D&D 5e. Any Dungeons and Dragons 5th edition product that's using material beyond the SRD and isn't licensed to do so by WotC is in violation of US copyright and/or trademark laws unless it falls into one of several narrow categories of works exempt from said laws.
The site you link does not describe a special license agreement, so when the first result I saw included the Goliath playable race--a race not in the SRD--I knew already that it was very probably living outside the law.
[Note that products distributed through DMs Guild hew to their own license: read their help pages for some more info. I've personally found their staff to be very responsive: do reach out to them if something's not clear.]