If you post a work on a public site, without explicit copyright, you are STILL granted copyright. You typically also give permission to the site (implied, or otherwise) to store and post that public work... But that permission isn't transitive. Twitter basically says "by posting to our site, you give us permission to republish it, as well as other users to republish (retweet) ON OUR SITE" BUT it is generally considered that 140 chars isn't creative enough to warrant copyright protection. If that was a case, I could easily write a post to generate all possible tweets, and then no one would be able to tweet. jsfiddle says "All code belongs to the poster and no license is enforced." Which means if you post to jsfiddle, you still own the copyright. I'm not a lawyer, but I would expect that if you posted something to a site like jsfiddle, you are actually giving implicit permission for people to use your code. This would be different than to you posting your code to your own personal blog.