It's been like 6+ months since I last experimented with Beacon... but these are the notes I took that worked for me regarding Beacon to dev sandbox access; From project folder, run from terminal; - "npm install @roll20-official/beacon-sdk@latest" to install beacon sdk - include info for beacon sandbox in your sheet.json; { "advanced": true, "advancedPort": 7620 } - "npm run sandbox" will sync with roll20 sandbox on port 7620 Hope that helps. Also, not 100% sure, but you may have to get permission from Andrew (or similar roll20 staff) as well in order for the sandbox-beacon to be allowed. Probably best to post in the discord group though.