Our Go! Extensions, like many others, is hosted by the Scratch Foundation on the ScratchX.org website, rather than the regular Scratch website (scratch.mit.edu). Unlike the regular Scratch website, the ScratchX version of the Scratch programming environment is “open” in the sense that it can interact with other websites or computer hardware.
Here is what the Scratch Foundation has to say about ScratchX:
“ScratchX is a separate experimental platform built to test experimental Scratch features, also known as Experimental Extensions. There is no login or community component to ScratchX, and projects created within ScratchX can only be run on ScratchX.
The Scratch Team has created ScratchX to enable people to create and test Experimental Extensions. However, the Scratch Team does not endorse, support or maintain specific Experimental Extensions. People using Experimental Extensions should be careful not to provide any personal details such as login passwords or personally-identifiable information if prompted by an Experimental Extension.”
Since extensions run through ScratchX can come from many sources, opening a ScratchX extension will always trigger the following pop-up:
Our Go! Extensions, like the others in the ScratchX gallery, have been vetted by the Scratch Foundation and are safe to use. Our Extensions only connect your Scratch project to a Go!Temp, Go!Motion, or Go!Link, and will neither access other parts of your computer nor gather any other data.