Textbooks:

Tae Kim Grammar Guide – an in depth look at basic Japanese grammar curated by Tae Kim, which is possibly one of the highest regarded grammar guides you can find online for free.

Tobira 1: Beginning Japanese (this series continues with tobira 2)

1000 Essential Vocabulary for the JLPT N5 (this series continues all the way up to N1)

Remembering the Kanji 1 (this series continues with RTK2 & RTK3)

A Dictionary of Basic Japanese Grammar

Other Reading:

News Web EASY – a news website that attempts to make reading easy with furigana.

Basic Japanese Cheat Sheet – cheat sheet of basic grammar.

ItazuranekoDokushoclub – collection of graded readers and other reading resources.