Basically all kinds of applications you use through the internet you can build the server in those technologies you listed. You can't go wrong with any of them.
For backend development, I believe Node and Java have more opportunities, while Python is the number one in Machine Learning/Data Science.
TL;DR
Java -> may have more job opportunities for backend development
Node -> more versatile since you can create backend, frontend, and mobile applications with one language
Python -> increasing popularity because of DS/ML
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For software engineers, what kind of opportunities/markets would learning NodeJs, Java Spring, or Python Django be useful for?
Basically all kinds of applications you use through the internet you can build the server in those technologies you listed. You can't go wrong with any of them.
For backend development, I believe Node and Java have more opportunities, while Python is the number one in Machine Learning/Data Science.
TL;DR
Java -> may have more job opportunities for backend development
Node -> more versatile since you can create backend, frontend, and mobile applications with one language
Python -> increasing popularity because of DS/ML