TV Channels and streaming services that regularly show stand-up specials:
- Comedy Central: www.comedydirect.com/
- EPIX: www.epix.com/originals/epix-comedy-specials
- HBO: www.hbo.com/comedy
- Hulu: www.hulu.com/tv/genres/comedy/stand-up-comedy
- Netflix: www.netflix.com/
- Next Up: nextupcomedy.com/
- Seeso: www.seeso.com/view/stand-up (discontinued)
- Showtime: www.sho.com/comedy
- Vimeo: vimeo.com/ondemand/discover/standup

Resources I used for this list:
2015 in stand-up comedy (Wikipedia)
2016 in stand-up comedy (Wikipedia)
2017 in stand-up comedy (Wikipedia)
2018 in stand-up comedy (Wikipedia)
2019 in stand-up comedy (Wikipedia)
2020 in stand-up comedy (Wikipedia)
List of original stand-up comedy specials distributed by Netflix (Wikipedia)

Also check out my spin-off list on Documentaries about Comedy.