Protobuf to JSON

How to Use

Schema → Sample JSON (default mode)

1. Paste your .proto schema in the left panel.
2. The tool auto-detects all message types and populates the dropdown.
3. Select a message type and click Generate JSON.
4. A sample JSON with default field values appears on the right.

Binary → JSON mode

1. Switch to the Binary → JSON mode using the toggle.
2. Paste your .proto schema in the top textarea.
3. Paste your encoded binary data (hex or base64) in the second textarea.
4. Select the message type and click Decode Binary.

Proto3 Syntax Quick Reference

syntax = "proto3";

package myapp;

message User {
  string id = 1;
  string name = 2;
  int32 age = 3;
  repeated string roles = 4;
  Address address = 5;
  UserStatus status = 6;
}

message Address {
  string street = 1;
  string city = 2;
  string country_code = 3;
}

enum UserStatus {
  UNKNOWN = 0;
  ACTIVE = 1;
  INACTIVE = 2;
}

Field Types Reference

• Scalar types: double, float, int32, int64, uint32, uint64, bool, string, bytes
• Repeated fields: prefix any field with repeated — maps to JSON arrays
• Nested messages: use another message type as a field type
• Enums: define with enum, first value must be 0
• oneof: only one field in a group can be set at a time

Privacy

All processing is client-side. Your schema and binary data are never uploaded or stored.