XML to Protobuf Converter

Example: XML input and real Protobuf output

The output below was generated by the same conversion code the converter uses, run on this sample when the page was built.

<catalog>
  <book id="bk101">
    <title>Designing Data-Intensive Applications</title>
    <author>Martin Kleppmann</author>
    <year>2017</year>
  </book>
  <book id="bk102">
    <title>The Pragmatic Programmer</title>
    <author>Andrew Hunt</author>
    <year>1999</year>
  </book>
</catalog>

catalog {
  book {
    title: "Designing Data-Intensive Applications"
    author: "Martin Kleppmann"
    year: 2017
    @_id: "bk101"
  }
  book {
    title: "The Pragmatic Programmer"
    author: "Andrew Hunt"
    year: 1999
    @_id: "bk102"
  }
}

Protobuf output is 16% smaller than the XML input. The same data is 214 characters as minified JSON and 341 as pretty-printed JSON. Sizes are character counts, not tokens: token counts depend on the model's tokenizer (see the tokenizer comparison).

XML to Protobuf: what changes

• Reading XML: Attributes are kept with an @_ prefix (id="bk101" becomes "@_id"), repeated child elements become arrays, and numeric text becomes numbers. A single child element becomes an object, not a one-item array, so the shape depends on how many elements appear.
• Writing Protobuf: Output is Protobuf text format: arrays become repeated fields and nested objects become message blocks. To encode binary Protobuf you still need a .proto schema with matching field names and types, and keys like @_id or opt-level are not valid field names.

Why Convert XML to Protobuf?

Use Protobuf for high-performance internal APIs, microservices communication, or when you need maximum efficiency and have defined schemas.