Scott C. said: Your problem is going to be that you won't be able to test anything. the javascript for sheetworkers is just regular es6 javascript, but functions like get/setAttrs are unique to Roll20, and are your only way to interact with the sheet in the sheetworkers, so you won't have any idea if your sheetworkers are actually functioning until you test it live. Yeah, I understand that. My original "plan", if we can call it that, was to develop the general layout and add the Roll20-specific stuff after I purchase Pro. Arguably this would still give me a headache. I have another question regarding JavaScript: you say Roll20 uses ES6, if I use that as well, that means when I start developing on Roll20, the functions I had written locally would still work, correct? For instance, I have a few tabs (<li> items) that expand when clicked on, which uses JS. Would my tabs still work on Roll20 or would I have to rewrite them? (pic below for clarity) G G said: Scott C. said: Your problem is going to be that you won't be able to test anything. And this is a really big deal. If you build your sheet completely, and then convert it over to roll20, chances are you will have many, many issues, big and small, to track and fix, and it will be very frustrating to deal with them all at once. it is much easier to build the sheet and test it while building, dealing with each issue as it arises. Like I said above, my current "plan" consisted of making visuals, leaving the scripting for when I inevitably purchase Pro. But I can understand that developing blindly will lead to issues. I suppose the best course of action is to wait a bit until my schedule settles and purchase a Pro account then to fully benefit from the subscription time. Thanks for everyone's opinion! You cleared a few things for me. I think I'll wait before I continue developing any further.