Depends on language, I've build GraphQL servers in a few, though mostly JavaScript and Python. For Python I used to use Graphene, these days I use Strawberry.
For JavaScript, I originally used graphql-js and express-graphql, as these were the original libraries and I was a literal day 1 adopter. All the libraries are essentially just wrappers around graphql-js, so it's still viable to use directly. But for schema-building I now use Pothos (https://pothos-graphql.dev/), I'd probably use graphql-helix as the http layer (https://github.com/contra/graphql-helix).
