I recommend to use Firebase as Backend for small application and Node. JS as Backend for Larger Application in Flutter App Development. A flutter/dart package allows you to create a backend server.
Read moreIs Dart faster than NodeJS?
It’s actually faster than other compiled languages like Java. However, Dart proved to be much faster when benchmarked against JavaScript . You can refer to the benchmark of Dart against NodeJS here.
Read moreWhich is best for backend?
Here are the details of the best backend frameworks.
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