You might like to read Ekamsena Sutta (AN 2.18), on the consequences of good and bad conduct.
There's a famous (non-Buddhist) saying, in English, for children
"If You Can't Say Something Nice About Someone, Don't Say Anything at All!"
Following that advice that might be even easier on social media, because you have time to think before you post.
Is there a good way to use "reputation", too?
Given that I have declared, Ananda, that bodily misconduct, verbal misconduct, & mental misconduct should not be done, these are the drawbacks one can expect when doing what should not be done: One can fault oneself; observant people, on close examination, criticize one; one's bad reputation gets spread about; one dies confused; and — on the break-up of the body, after death — one reappears in the plane of deprivation, the bad destination, the lower realms, in hell. Given that I have declared, Ananda, that bodily misconduct, verbal misconduct, & mental misconduct should not be done, these are the drawbacks one can expect when doing what should not be done.
I've been conversing online since the earliest 1990s. I don't remember being mean to people but there were times I got into silly (friendly) chats and conversations with people, using a pseudonym.
Since then I tend to post, instead, with a username that's more-or-less identifiable as a real person
I'm not saying that you need to investigate which person I am -- but, "I" recognise what I post as being "my" username and "my" post and so on -- maybe you don't want to post stuff that you ought to feel ashamed of ...
Given that I have declared, Ananda, that good bodily conduct, good verbal conduct, & good mental conduct should be done, these are the rewards one can expect when doing what should be done: One doesn't fault oneself; observant people, etc.
... so adopting some kind of "identity" -- as if this were in public, not in private -- might help to "take responsibility".
And since you asked for Buddhist advice, how about No Attachment to Dust:
Even though alone in a dark room, be as if you were facing a noble guest
Karmically speaking, would online communication be a lesser consequence than actual in person wrong speech?
Perhaps it's greater consequence:
- Read by more people
- Remembered for longer
- Less immediate consequence
If you're talking in person and (for example) you offend, there's immediate consequence -- they reply -- and you might correct was said and why you said it.
Whereas with fewer immediate "consequences" to what you post online, there's less feedback or correction -- and maybe what you do, say, and think are more likely to become "habitual".