Charted does not store the data it visualizes. Each time Charted loads, it only re-fetches the data from the link provided. To give you a shareable link, Charted also embeds the url string that you provide within the link that Charted generates for you. Thus, the publicly-hosted charted.co can only fetch data and provide shareable links for data files that are already publicly accessible to anyone with the link.
We use Google Analytics to measure traffic on charted.co. Google Analytics does not store the file’s data either, but it does automatically log Charted links (which include the embedded data file’s url string). Therefore, the url string you input may be logged by Google Analytics and subject to their privacy practices.
We believe charted.co has sufficient privacy protections for most purposes, but for especially sensitive data we recommend serving your own instance of the open-sourced Charted. At Medium, for example, we host an internal instance of Charted with links only accessible on our secure network.