Best format guide

Best Data Format for APIs

JSON remains the default for most APIs, with Proto for strongly typed high-throughput services.

Recommendation

Choose the default first.

JSON

JSON is human-readable, ubiquitous across stacks, and easy to inspect/debug in API workflows.

application/json

PROTO

Use Protocol Buffers for typed contracts and compact payloads in RPC services.

Files: 9

GRAPHQL

Use GraphQL schema files for query-driven APIs and type-governed contracts.

Files: 9

Decision factors

Ground the recommendation in constraints.

Decision Factors

  • Client ecosystem and tooling compatibility.
  • Need for strict contract typing and generated clients.
  • Payload size/performance requirements at scale.
  • Debuggability requirements for support operations.

Common Mistakes to Avoid

  • Picking a binary format without considering debugging burden.
  • Skipping versioning/backward-compatibility strategy.
  • Mixing schema evolution policies across services.
FAQ

Answer the common objections directly.

What is the primary recommendation in this guide?

JSON is the recommended default for this use case.

How should teams validate this format choice?

Use sample fixtures and manifest endpoints to test compatibility, performance, and conversion behavior in production-like conditions.