I just now came across this post. Here goes. These are my favorites I've gathered over the years.
Dictionaries
Dict.cc. It's got tons of entries, especially for the words that get used in daily life. Almost all of the entries have an audio example from a native speaker.
Leo. Also rock solid. It has example sentences and very good grammar explanations. The grammar section is all in German.
General resources
Your Daily German. Ten years' worth of grammar and vocabulary explanations for all levels. Want to really understand prefix verbs? Come read some explanations with unicorns and squirrels, and see if they don't make sense in a way you can't find anywhere else. If you're not sure where to start, check out the series on word order.
Easy German YouTube channel and podcast. Pretty well known by now, and for good reason. The Super Easy German series on YouTube is a good place to start. The podcast is also a great resource. The transcripts and Discord server are well worth the $5-6 per month on Patreon.
Deutsche Welle. A free program for all levels from a German public broadcaster. Interactive exercises and easy to use website. This program includes Nico's Weg.
Grammar
Grimm Grammar. A free site run by the University of Texas. The explanations are very easy to understand and cover all of the important topics. Includes audio and exercises.
Nthuleen. A classic for simple grammar explanations and exercises. She covers basic and advanced topics. The exercises are not interactive, but don't let that scare you off.
Dartmouth review of German grammar. It's a bare bones website with helpful explanations of the most important topics. The articles on separable and non-separable verbs are great if you want to do a deep dive.
YouTube channels
Lingoni German. Formerly known as German with Jenny. Her explanations are easy to understand. Lots of examples. Subtitles in English and German. The videos are labeled by level.
Learn German with Anja. Whatever topic you're having trouble with, Anja can break it down and make it fun. Most of her videos are for the A and B levels.
Deutsch für Euch. She covers a lot of ground. How to talk about specific situations, grammar, pronunciation. It's not one of the huge channels, but worth checking out.
Pronunciation
Paul Joyce pronunciation guide. Simple, written explanations of the different consonant and vowel sounds, with some audio examples.
Fröhlich Deutsch. Her channel is the place to be if you want to learn how to say the vowels and fine-tune your pronunciation. German only. (Forget the R. You can say it a lot of different ways. The vowels are critical to being understood).
Deutsch mit Benjamin. A great resource for listening and pronunciation at an advanced level. He takes examples from TV shows and explains how the pronunciation works. German only.
Modern German Pronunciation. This is a book that explains German pronunciation for native English speakers, in English. Very detailed. Good if you're advanced and can handle some technical explanations.
Hey, ich hoffe, es macht dir nichts aus, wenn ich dich ungefragt korrigiere, bitte nimm's mir nicht übel :)
Du hast "favourite" hier mit "beliebteste" übersetzt. Das ist nicht direkt falsch - "favourite" kann in bestimmten Kontexten so übersetzt werden. Aber normalerweise wird "beliebt" benutzt, wenn es um etwas geht, was sehr viele Leute gut finden, also eigentlich eher im Sinne von "popular". Eine App ist "beliebt", wenn viele Leute sie gerne benutzen.
Wenn du nach "favourite thing" von einzelnen Personen fragst, also nach der Meinung von Individuen, dann ist die einfachste Lösung "eure Lieblings-Apps". Für mich persönlich klingt "Lieblings-" immer ein bisschen nach starker emotionaler Bindung ("your most beloved apps"), deswegen würde ich wahrscheinlich schreiben "Apps, die ihr gerne nutzt" oder "Apps, die ihr empfehlen könnt".
Nochmal, ich mein's nicht böse, aber ich hab Übersetzung gelernt und stolpere sehr oft über (unfreiwillig) "schräge" Übersetzungen, die mir dann keine Ruhe lassen.