"on here" vs "in here" for websites

"Be skeptical of what you read on here" is correct for this website. "On here" refers to like websites and stuff, "In here" refers to places, and being "in" somewhere. (Sorry, I know my wording's not professional; I'm in high school, but I'm trying to help you out the best I can here.) :)

I think it comes down to context. Some websites, particularly where small(ish) or common interest groups hang out with each other, feel to users like a place they inhabit, so "in here" is appropriate for them. Similarly for chat servers. For most websites, "here" or “here on [site name]” would make more sense. I think most people prefer "on this [web]site" to "on here", which sounds slightly awkward to my ears.