In order for Scratch to be accessible, the following servers need to be allow listed (i.e., not blocked) by your network:
If you can use wildcard domains:
*.scratch.mit.edu
*.recaptcha.net
*.gstatic.com
*.wistia.com
*.wistia.net
*.akamaihd.net
If you can't use wildcard domains, this is the current list of every subdomain. However, we add new services under subdomains frequently, so this list could get out of date over time:
scratch.mit.edu
api.scratch.mit.edu
projects.scratch.mit.edu
cdn.scratch.mit.edu
cdn2.scratch.mit.edu
assets.scratch.mit.edu
clouddata.scratch.mit.edu
download.scratch.mit.edu
downloads.scratch.mit.edu
uploads.scratch.mit.edu
fonts.gstatic.com
wistia.com
fast.wistia.net
embedwistia-a.akamaihd.net