I've seen a couple of episodes of Hazbin Hotel that were randomly in my suggestions from Youtube. Thry were pretty good.
The only episode available on Youtube (legally, though the first Amazon Prime episode was posted officially for a limited time) is the pilot, which was done by Vivziepop and the Spindlehorse animation group as a sort of proof of concept of what she wanted the series to be about, and it's still somewhat loosely canon to the main series (though the cast were replaced, as Vivziepop wanted to favour Broadway actors where she could, though some would go on to play roles in the main series, or
Helluva Boss). Here it is if you want to watch it, but keep in mind, it's pretty gruesome, has sexual references and swear words, and is definitely NOT for kids, and probably not SFW...
That being said, the first half of the second episode of the main series is also available on Youtube. In addition,
Helluva Boss is available in its entirety on Youtube. Recently, a deal was struck with Amazon Prime, so that while
Helluva Boss episodes will premiere uncensored on Prime (along with a few bits of enhanced animation), censored versions (not in terms of language but the more...explicit acts going on) will be released for free on Youtube a month after their premiere, with the first such release being the revised pilot episode,
Mission Zero. In addition, the Helluva Shorts episodes seem like they have a simultaneous release, unless they're not on Prime, anyway...