Shut Up is designed with privacy in mind, and it does not collect any information which can be used to personally identify you. However, there are a couple of technical considerations you should keep in mind when using it.
Shut Up uses a CSS file called shutup.css by Steven Frank to hide comments on a large number of websites. This file is used across all versions of the extension. Due to the frequently-changing nature of web design, this CSS file needs to be updated periodically to guarantee its efficacy. Except on Firefox, all other versions of Shut Up periodically update this file from this server. The connection is always encrypted.
During CSS update checks, your device's external IP address and the version of Shut Up you're running is temporarily stored in my server logs for diagnostic purposes. Logs are retained for one week. Please email me if you have any questions about my data retention policies.
Because AMO has a policy against extensions which update code from external sources, the Firefox version of Shut Up disables the CSS update feature. Instead, the extension will be updated more frequently through AMO to ensure that everyone has the latest stylesheet.
Shut Up includes a whitelist feature, which lets you see comments on your favorite sites if you so choose. This whitelist is stored encrypted on your device and is only read by Shut Up and your web browser. It's never shared.
Shut Up uses a Content Blocking API which is supported in modern versions of iOS. This API is architected in such a way that Shut Up can't know anything about your browsing activity. You can learn more about the API's design on the official WebKit blog.
You can opt-out of the automatic CSS update by going into your Settings app and turning off Background Refresh for Shut Up. You can learn more about the Background Refresh feature on Apple's support site.
If you opted into it when you set up your device, Apple will share anonymized usage statistics and diagnostics with me. You can read more about this feature on their support site. I treat your usage data with respect, and will never share or sell your information.
Lastly, when you open Shut Up, it will automatically scan your clipboard for any URLs you may wish to add to the whitelist. This check is completely automated and is done without accessing the Internet. The clipboard data is not stored without your explicit consent, and is only used for the whitelist feature.
If you have questions or concerns about anything in this document, please email me.