This might be a bit different from what you're looking for, but I highly recommend Dynalist.io; it offers every conceivable option for viewing anywhere any way you can imagine and offers 99% of the features for free (subscription plans are for duplicate backup versions as SimpleText on Dropbox or Google Drive, but I've never had any problems with their Amazon Cloud default).
The reason I say this is because I've read quite a few articles in the past on brain science stuff and apparently, the majority of brain anxiety most people encounter is from the brain running repeating cycles to simultaneously address/prioritize things that are on it's periphery radar that "can't be addressed immediately" ...
The simple act of quickly jotting everything down then acts as a sort of "Sudo Purge" and allows the brain to stop wasting cycles subconsciously trying to to address everything you have to deal with.
As an alternative, I find Cultured Code's "Things" app wonderful too.
Both of the services are as intuitive to use as a piece of paper with the option of dragging-and-dropping everything where-ever you want instead of endlessly copying-and-pasting and can be set up to either remain as simple as you wish or in the case of Dynalist.io (it was created by former Workflowy users who's versions they considered had become too full to easily navigate with Workflowy's "1-page is all you need" approach). To that end, Workflowy is great too, and both Workflowy and Dynalist not only allow for weblinks to interesting stuff you find/want to view/research later but Dynalist/Workflowy also have "save to" browser extensions so you can create your own private bookmarking service; in Dynalist you can pre-designate one of your pages as an "Inbox" where everything you clip is automatically saved to along with URLs and brief descriptions.
Dynalist in particular would be an "if I could only have one application" sort of deal ... you can use it for EVERYTHING from an organizer with due date reminders to project management to math (it has mathematical notation) to I believe music notation to coding projects to project management (you can designate pages for collaboration) to writing projects (it has a "word processing view" mode) to keeping notes/lists/recipes/images/whatever.
One of the reasons I would say it's invaluable for mental health purposes is that as you learn things that work for you, whether they be watching certain motivational videos or exercise routines or meditation routines or routines for taking whatever supplements/nootropics/whatever you find useful for your personal mental health, you'll more than likely want to have these routines written down and handy for days when "your brain doesn't feel that great" ... which is where an outliner-type list comes in handy for rapid reference.
Nirvana (sort of an online version of Things) is also pretty good, and if you find that too complex, "TeuxDeux" is great for clearing your head and making minimalist routines/shopping/to-do lists/weekly agendas in a very intuitive way.