ZoteroBib is a free and advertisement-free service, built by the team that created Zotero, that helps you build a bibliography instantly from any computer or device, without creating an account or installing any software.
If you need to create a bibliography to support a single paper or talk, and you do not plan on reusing the bibliography items again, then ZoteroBib could be the tool for you.
However, if you plan to use the bibliography items across multiple projects, or want to collaborate with others to discover and curate a library of bibliographic items (including full text) to support your ongoing work, then Zotero, the free, full-featured reference management software, would be the better tool.
Zotero also offers many more features: