Geographic masking is a technique used to basically move your data around so not to give away the exact geographic coordinates of individual level data.  This is done when locations of individuals (like in health data, crime data, or endangered species data) need to be “anonymized” so they cannot be re-identified through reverse geocoding.

One tool that does this is MaskMy.XYZ.  MaskMy.XYZ helps users perform a time-tested geographic mask from the scientific literature, known as donut masking. Instead of being a toolbox for a specific (potentially expensive) GIS software suite, MaskMy.XYZ uses popular open source JavaScript libraries to mask data without ever requiring users to install or download any software. So whether you’re a GIS expert who can’t be bothered to script this method yourself, or a GIS newbie who knows you need to mask your data but aren’t quite sure how, MaskMy.XYZ makes your life easier and brings previously cumbersome methods into reach.

Everything runs client-side in your browser, meaning there’s nothing to install, data never leaves your computer, and as a result nobody except you ever sees your confidential files. It is a safe and secure way to anonymize spatial data.  Finally, you can map your secret fishing spots and share them with others without giving away the exact locations!  Check it out!