This is Solunia

Best resource for grammar:

A short but nice course in Finnish, has multiple vocabularies:

This is just a demo but still useful:

https://materiaalit-koosto.otava.fi/web/state-jurdmmbvgaydeirmj4yq/649acb7ce5b1d718f439f971

Nice course on grammar with test tasks at the end:

https://openlearning.aalto.fi/course/view.php?id=158#section-0

Other courses at Aalto Open University:

https://openlearning.aalto.fi/course/index.php

Some good learning materials and tests:

https://openlearning.aalto.fi/course/view.php?id=59§ion=8

Very good series of basic videos for immigrants:

Another interactive learning site:

http://tasteoffinnish.fi/

Some listening exercises for learning basic words and phrases.

https://visnakker.no/tema.html

Very good short videos on basic word and phrases:

An online phrasebook with audio:

https://www.goethe-verlag.com/book2/EN/ENFI/ENFI002.HTM

English/Finnish tests from the same site:

https://www.goethe-verlag.com/tests/test/EN/FI/1/easy

A curious site where short news headlines are transcribed in pictures:

https://selkosanomat.fi/kuva/

Vocab quizzes:

http://iteslj.org/v/f/

Numerous Quizet vocab quizzes:

https://www.scoop.it/topic/oppitori/?tag=quizlet-mamu

A very nice short course, includes glossaries in English, French, Persian, Arabic and Russian:

A course of spoken Finnish:

https://extreme-finnish.teachable.com/

Finnish verb conjugator:

https://www.verbix.com/languages/finnish

A really good learning channel that has up to 15 subtitles in different languages:

A number of Free online courses:

https://www.savonia.fi/paivita-osaamistasi/muu-jatkuva-oppiminen/maahanmuuttajalle/suomen-kielen-kurssit-savoniassa/

A great resource for practicing grammar:

Free courses at the Open University of Vaasa:

Online learning materials, exercises, including audio ones:

https://salpro.salpaus.fi/hotpotatoes/

A nice channel with videos on language and also useful tips about life in Finland.