[Possible Spoilers]I have a crazy idea (and it's been brought up before) but hear me out: Stranger Things is indeed part of the Stephen King multiverse.

A theory was posted on Reddit last year about how ST may be a prequel to The Mist. However, I think it goes deeper than that.

1. Ever since the premier of Stranger Things, more content from the mind of Stephen King has been popping up on Netflix, i.e. 1922 and Gerald' s Game. I believe that they are trying to acclimate people to the mind of the man that people only have a taste of. Netflix knows of the successes of shared universes as seen by the Marvel Cinematic Universe. But, since Disney will be starting their own streaming service, they may lose the rights to Disney properties as well, such as The Defenders and Daredevil. They felt the need to continue with a universe that has many tendrils attached to it. So what do they do? Use the not so well known Stephen King multiverse to connect some of their content.

2. Many of the creatures shown as well as the reality they belong to show many similarities to one of the hidden realities created by King. How these kids are the focal point of the story and their home life (besides Will) have very little impact on the story is reminiscent of the way the children in IT are the focal point and are rarely shown at home.

Side Theory- The final season of ST will show the children grown up and show the effect the events have had on their lives.

3. References to King are placed everywhere throughout the show, including the desire for Will's mom's boyfriend Bob to move to Maine, the location for many events in King's stories.

There are more, but since it is nearly 3am when I am writing this, I can't remember other points I was going to make. But in my mind, it just makes sense. Let me know what you think of the idea and thanks for reading!

tl;dr Due to circumstantial real life events and references in the show, Stranger Things could be a part of the Stephen King multiverse.