I've been using https://www.wanikani.com since a few months and it's great. It's mainly for Kanjis but you learn vocabulary at the same time. It's free at first and then you have to pay, but I'm still at the free-period. (Everything is explained there don't worry :) ) what I like is that you have a lot of mnemonics and word association so you learn easily, + you've got a reminder at a specific time to learn easily. There are a few app that are linked to these website and that you can download on your phone
Tofugu is a great resource, IMO. I recommend browsing the site and checking out all the different pages --- they have a lot of information, guides, apps (like WaniKani and EtoEto), and resource links. If you're a beginner (like me), their guides for hiragana (+ a hiragana mnemonics chart here) and katakana would be a good place to start.
For extra practice, another place I go to is Jalup NEXT.