JSON to Protobuf

Convert a JSON sample into a Protobuf proto3 schema directly in your browser. The generated messages cover nested objects, arrays, scalar values, nullable data, and common timestamp strings.

Choose a root message and optional package, then adjust naming and nesting options. The converter keeps original JSON keys through json_name when a valid Protobuf field name must differ.

How JSON types are mapped

• Integer samples become int64, decimal samples become double, and strings and booleans use their matching scalar types.
• Nested JSON objects become messages. Keys that are not valid Protobuf identifiers are normalized and retain their original JSON name.
• Arrays become repeated fields. Object arrays can merge fields across multiple samples, with missing scalar fields marked optional.
• Null values, empty arrays, and incompatible mixed values use google.protobuf.Value so the generated schema remains valid.

Review the generated schema

Generation is based on the supplied sample. Review field numbers, numeric ranges, optional presence, enums, maps, oneof choices, and API compatibility before adopting the schema.

Related tools: JSON Formatter · Protobuf Formatter · JSON to TypeScript