This app was mentioned in 5 comments, with an average of 1.00 upvote
Whether app/online/institute is better really depends on your personal learning style.
I Learned Dutch before online or apps were an option, but I bought a cassette (remember those?) course and never got round to doing it because I'm a lazy bastard. It was only when I signed on to a course at my local college that I actually did anything about learning the language.
If I were starting from scratch now, I'd probably do a college course for the interaction with someone I could get real human feedback from, and supplement it with an app like Learn Dutch for vocabulary practice.
I've been using this app.
It is just for vocabulary training, so no good if you don't have the basics of the language, such as grammar, but if like me you need to improve your vocabulary it's ideal.
I get a lot of value out of listening to Dutch-language radio.
In the past I used Amsterdam's Radio Tien Gold, but that's now little more than a streaming jukebox. So now I listen a lot to VRT2 out of Antwerpen. The advantage of both is that being music-based you're not intensively trying to understand what's being said but you get breaks (and living in England, a far better range of music than any station here).
I still haven't got there, but with the help of the Learn Dutch app, I'm heading in the right direction.
I've been using this vocabulary trainer for years now and it's very helpful for learning new words.
https://play.google.com/store/apps/details?id=net.languagecourse.vt.nl
Mostly listening to Dutch & Flemish radio online. I find VRT 1 and (especially) VRT 2 have a good balance of speech and music so that I'm not having to work flat-out at comprehension but get a break during the records.
(Learn Dutch Vocabulary)[https://play.google.com/store/apps/details?id=net.languagecourse.vt.nl] is quite a decent app for vocabulary practice. It's broken down into quite small chunks so you can dip in and out as time allows.