www.j-talk.com Transliterate and gloss Hiragana/Romaji/Katakana
www.outlier-linguistics.com Japanese and Chinese blogging and dictionary producer (Pleco, on the Chinese side)
www.valiantls.com Valiant-Japense: a physical school - with many useful free posters
www.tofugu.com about Japanese topics to help people who want to visit Japan, live in Japan, and/or Learn Japanese.
www.nihonshock.com cheat-sheets - basic one for free: http://cheatsheets.nihonshock.com/sheets/basic-japanese/
www.mlcjapanese.co.jp Free study materials
www.happylilac.net Free printables in japanese for any school subject
www.kawakawalearningstudio.com Kawa-Kawa - podcasts for posters (for Japanese + Mandarin-Chinese btw)
www.jlptstories.com JLPT Stories is a podcast and companion site based in Shinjuku that provides stories in Japanese, labeled with their intended JLPT (Japanese Language Proficiency Test) level. Each three to four minute story is written and read by a native Japanese speaker at normal speed.
https://bilingualnews.jp/podcastpage/ Bilingual News is a free podcast that began in 2013 and releases episodes every Thursday. Michael and Mami discuss world news in a mixture of English and Japanese.
www.aozora.gr.jp インターネットの電子図書館
www.play.google.com/store/apps/details?id=com.bunpoapp Bunpo is a Japanese grammar study app
www.warodai.ru Large Japanese-Russian Dictionary
www.kotobank.jp 出版社などが提供する信頼性の高い辞書・辞典・データベースから 用語の意味を一度に検索できるサービスです
www.suiren.io a Kanji Relationship Explorer
www.onomatopedia.jp Online onomatopoeia encyclopedia aims to teach Japanese onomatopoeia using illustrations, videos, and English equivalents.
www.kai.kanjiapi.dev kanjikai is a rabbit-hole kanji dictionary: every kanji and every reading is clickable