Protobuf Text ↔ JSON Converter

Convert Protocol Buffers text format (also called prototext or textproto) to JSON and back, right in your browser. Paste a message, pick a direction, and get a clean, indented result — no .proto schema, no compiler, no upload.

This is a schema-less, structural converter. It maps the shape of the data, not its wire encoding: it does not decode or produce binary protobuf. If you have the human-readable text form (name: "Alice", nested { } blocks, repeated keys), this tool is for you.

How to use it

1. Paste your Protobuf text format or JSON into the Input box.
2. Choose a Direction:
   • Protobuf Text → JSON turns prototext into a JSON object.
   • JSON → Protobuf Text turns a JSON object back into prototext.
3. Pick 2 or 4 space indentation for the output.
4. The Result updates automatically. Copy or download it.

What gets converted

• Scalars — quoted strings, integers, floats, and true/false booleans.
• Nested messages — a field { ... } block (or the older field < ... > form) becomes a nested JSON object.
• Repeated fields — a key that appears more than once collapses into a JSON array, and JSON arrays expand back into repeated keys.
• Enum values — bare UPPER_CASE identifiers stay unquoted when writing prototext and become plain strings in JSON.
• Comments — # line comments in prototext are ignored while parsing.

Example

Prototext input:

name: "John Doe"
id: 1234
address {
  city: "Springfield"
}
tags: "developer"
tags: "golang"

Becomes JSON:

{
  "name": "John Doe",
  "id": 1234,
  "address": { "city": "Springfield" },
  "tags": ["developer", "golang"]
}

Why isn't this the same as binary protobuf?

Binary protobuf encoding requires a .proto schema so it knows each field's number and type. Text format is self-describing enough to read structurally, which is why this converter can work without a schema. Use it for debugging log dumps, fixtures, and config in text format — not for parsing .pb binary payloads.

Does my data leave the browser?

No. The conversion runs entirely client-side in your browser. Nothing you paste is sent to a server.