Service Alert
There are plenty of websites that will generate a reference if you plug in a web address or pdf. However, the references that you can get from OneSearch, databases, or Google Scholar are usually just as good as those from an online citation generator.
The 2 tools below, Mendeley and Zotero, are much more powerful tools that not only generate references, but they also enable you to store and organize your research. They can also generate in-text citations and full bibliographies.