JSON to Protobuf message (proto3)

How to use it

1. Enter json input and root type name.
2. The result appears straight away and updates as you edit.
3. Copy the result, or copy a link that keeps the same values to share it.

How it is calculated

string, int32 or int64, double and bool, repeated for arrays, and a message per object with field numbers from 1 in key order. Names are snake_case with json_name when the derived name differs from the key, and null on a scalar adds optional. Mixed values use google.protobuf.Value.

Example

Inputs: Root type name = Root. Result: Generated code: syntax = "proto3"; message Root { int32 id = 1; string name = 2; string email = 3; bool is_active = 4 [json_name = "is_active"]; double balance = 5; repeated string tags = 6; Address address = 7; repeated Order orders = 8; } message Address { string city = 1; string postal_code = 2 [json_name = "postal_code"]; } message Order { string order_id = 1 [json_name = "order_id"]; double total = 2; optional string coupon = 3; }; Types generated: 3; Fields: 13.

{
  "id": 1024,
  "name": "Sara Ahmed",
  "email": "sara@example.com",
  "is_active": true,
  "balance": 1520.75,
  "tags": ["vip", "riyadh"],
  "address": { "city": "Riyadh", "postal_code": "12211" },
  "orders": [
    { "order_id": "A-1", "total": 99.5, "coupon": "EID10" },
    { "order_id": "A-2", "total": 120, "coupon": null }
  ]
}

syntax = "proto3";

message Root {
  int32 id = 1;
  string name = 2;
  string email = 3;
  bool is_active = 4 [json_name = "is_active"];
  double balance = 5;
  repeated string tags = 6;
  Address address = 7;
  repeated Order orders = 8;
}

message Address {
  string city = 1;
  string postal_code = 2 [json_name = "postal_code"];
}

message Order {
  string order_id = 1 [json_name = "order_id"];
  double total = 2;
  optional string coupon = 3;
}

Limits and caveats

• In the official Protobuf JSON mapping, int64 is printed as a quoted string.
• Field numbers follow key order; do not change them once messages are in production.