I feel like a “trsuted third-party website” would be a really bad decision to save/store data to using HTTPService, because I’ve had more HTTPService fails than roblox datastore fails (which barely happen). You can use ProfileService to save your data, its good and I’ve gone through the code and I can say its highly unlikely that it will fail to save data.
BUT as a good developer, I would recommend you to first learn to save data manually, which rarely fails to save or load if you do it the right way. I have always used my own manual method, the general method of a pcall function to save/load data. It took me a while to come accross profile service and I would say its still one of the best open source modules for datastores.
Besides profile service, there is DataStore2, which I never used but I’ve seen some people say its inferior and not to recommend using it.
To wrap it up, after looking at top results, I would say ProfileService still stands to be the most famous and best to rely on datastore opensource module in roblox.