Chapter 29: Custom Serializers and Codecs

Beyond Protobuf

gRPC defaults to Protobuf but supports pluggable serialization:

• Protobuf (default): application/grpc+proto
• JSON: application/grpc+json (useful for debugging)
• FlatBuffers: zero-copy deserialization
• Custom: implement the Codec interface

When to Use Non-Protobuf

• JSON codec: debugging, interop with systems that can't use protobuf
• FlatBuffers: extreme performance (avoid deserialization entirely)
• Custom: legacy wire formats you must support

In practice, 99% of gRPC services use Protobuf. Don't change unless you have a measured reason.

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