Where is my poll data stored?

All of it stays on your own site. Your polls, the options you set, and every vote your visitors cast are stored in your WordPress database, on your own hosting.

OpinionCamp is entirely self-hosted. There is no OpinionCamp account holding your results, no external dashboard, and no third party with a copy of your data. If you back up your WordPress database, you have backed up your polls and their results.