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Flat JSON to Protocol Buffers

Generate a proto3 message with numbered fields for non-null primitive JSON values.

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Flat JSON to Protobuf online

Generate a proto3 message with numbered fields for non-null primitive JSON values. Use this when inspecting structured input or preparing a data or code artifact. Generated commands and configurations remain text until you review and use them yourself.

How to use it

Paste JSON matching the structure in the example. Choose Run tool. Review the output, then copy or download it.

Worked examples

Use this when inspecting structured input or preparing a data or code artifact. Generated commands and configurations remain text until you review and use them yourself.

Reproducible worked example

Settings: No additional settings.

Input:

{ "name":"Anna", "count":3, "active":true }

With the input and settings above, the tool produces:

Output:

syntax = "proto3";

message Generated {
  string field_1 = 1; // JSON field: name
  double field_2 = 2; // JSON field: count
  bool field_3 = 3; // JSON field: active
}

The example output has 7 lines. Compare its order, separators and whitespace with the input before copying the result.

Limitations and common mistakes

  • Generates a starting type declaration from observed fields, not a complete application or an authoritative data contract. Review names, nullability, numeric precision and serialization dependencies.
  • Combined input is bounded to 150,000 characters; output text is bounded to 1.2 million characters. Some algorithms impose smaller limits, stated in their error messages.

Frequently asked questions

What format should I enter?

Paste JSON matching the structure in the example. The worked example shows the supported structure and actual output.

How can I create a proto3 message with numbered fields for non-null primitive JSON values online?

Paste JSON matching the structure in the example. Choose Run tool. Review the output, then copy or download it.

Where is my input processed?

The bundled tool processes input in your browser. It does not upload tool input to a conversion service. Other site plugins, analytics, advertising and browser extensions may have separate behavior.

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