Anki is spaced repetition flash card system. By gradually spacing out the flash cards over time, your learning will become reinforced as you can recall the information over longer and longer periods of time. Anki is free on the computer and $25 on mobile devices.
Japanesepod101 is a subscription based podcast website, with plenty of listening practice ranging from “absolute beginner” to much more advanced podcast sessions. The post lots of free content to YouTube, but if you want the whole sha-bang you will need to pay a monthly fee. They have lots of monthly discounts so I would just wait until a good one hits the store. I was lucky enough to buy in during a 65% sale, but as of recently its been on 25% discount. I would personally recommend this program since it comes with an app as well, so you can download lessons and listen to Japanese content on the go.
Tofugu is a great introductory resource. It’s the website I learned to use Hiragana and Katakana for free. They also provide lots of up to date cultural information, interesting articles, and lots of grammar information. If you are brand new to Japanese I would recommend checking out their Hiragana page.
KanjiDamage is another great free resource for studying Kanji. It provides lots of free sometimes even entertaining mnemonics, examples, and definitions for Kanji.
Wanikani is a subscription based Kanji learning service, with that being said you can use a lot of their website for free to look up Kanji definitions and mnemonics. They also provide around 5 levels worth of lessons for free if you create an account.