Binary encoding formats offer many advantages such as compact storage, fast encoding/decoding, and well thought out ways to evolve your schema. But they often require a great deal of developer buy in with DSLs and distinct compilation steps. Avro has the same advantages as other binary encoding formats but has a superior developer experience.
Most back end services will accept input by way of JSON. After verifying that the JSON is well formed there is a large amount of validation that will need to performed such as:
A class of libraries called schema validators solve this problem in an elegant and declarative way.
Most back-end services will end up making calls to a relational database. The two most popular ways to do this are with raw SQL, or using a an Object Relational Mapping (ORM) library. But there is a third level of abstraction out there called a query builder. I believe that of the three approaches the query builder one is the best.