Good question ;)
This documentation page answers question from here asked by one of user interested in nanoexpress
nanoexpress implements middleware layer and these features
- Auto-document with
Swagger - Autovalidate with
Ajv - Auto-serialization with
fast-json-stringify
Also, nanoexpress will be faster, but not in all applications.
Last three features isn't available even on express as built-in, but nanoexpress gives these features and built-in.