Dear friends using Rextester
I think the users should be informed that Plagiarism check tools can detect the codes that you put on a wall and this can cause you problems when you publish your papers with the same code in it. It is difficult to explain the publishers that the code is put in rextester by you not by someone else. I had 2 cases when I was rejected for considering the paper because of this.
Recommendation for admins. Make the authors of the codes identifiable.
Recommendation for authors: Don't put everyhting on rextester.