replier
/ˈrɛplaɪər/Definitions
1. noun
A person or thing that replies or replies, especially a person who responds to questions or comments on the internet or in social media.
“The forum’s moderator was a well-known replier to controversial topics.”
2. verb
To respond to a question or comment, especially on the internet or in social media.
“Many people replied to the post with their thoughts on the issue.”