Yes, you are welcome to run a stand-alone study without subscribing to any other Ocean Platform services (ie. Ocean Tablets and/or Ocean Online Messages). In this scenario, participants can access the study using a public URL. All submissions via the public URL will be anonymous and will not generate a participant key (required for longitudinal research).
If you plan to track study participants over time, a participant key is required. In this case, a subscription to Ocean Tablets or Ocean Online Messages is required.