I thought I would kick off with some of my favourite internet sites

https://www.duolingo.com/

https://www.spanishpodcast.net/listado-episodios/ - good clear Spanish and well explained albeit all in Spanish

https://www.brainscape.com/packs

https://www.spanishdict.com/translation - great dictionary and grammar sections

https://www.linguee.com/ - put in a word or sentence and up come many examples of how to use the word or phrase

Please add your own favourites in this thread.