Mainsail understands the need for data privacy and it has been designed to only run in your browser locally.
Accessing my.mainsail.xyz stores the .html, .js and .css files for Mainsail locally in your browser's storage in exactly the same way that an instance running on your local hardware would do. There is no functional difference or concerns between accessing Mainsail locally or in a remotely public hosted instance.
Running Mainsail both locally and remotely in parallel is also possible.
Mainsail does not modify any third party packages and does not control Data Privacy for any third party packages you choose to install.
If you are concerned, please review the privacy policies for the following third party software:
Please contact the developers of any of the above software if you have any concerns.
It is worth noting that Klipper, Moonraker and Raspberry Pi OS are open source software. This does not bring a guarantee of privacy and security, but the source code is available and open to peer review.
The Raspberry Foundation is a registered charity in the United Kingdom with extensive Privacy and Safeguarding policies.