A Note on Downloads for Apple's MacOS Apple now marks packages (tarballs and the like) as "contaminated" when downloaded from a browser (they want developers distributing software from their App Store). But the packages can be safely downloaded with these commands from a terminal window without any problem: For Intel x86_64 PreBuilt: curl -O https://acdl.mit.edu/ESP/PreBuilts/ESP126-macos-x86_64.tgz -o ESP126-macos-x86_64.tgz For Apple arm64 (M-chip) PreBuilt: curl -O https://acdl.mit.edu/ESP/PreBuilts/ESP126-macos-arm64.tgz -o ESP126-macos-arm64.tgz For build from source: curl -O https://acdl.mit.edu/ESP/ESP.tgz -o ESP.tgz -- and (for Intel x86_64) -- curl -O https://acdl.mit.edu/ESP/OCC781-macos-x86_64.tgz -o OCC781-macos-x86_64.tgz -- or (for Apple arm64 M-chip) -- curl -O https://acdl.mit.edu/ESP/OCC781-macos-arm64.tgz -o OCC781-macos-arm64.tgz