Free JSON to XML converter

JSON (JavaScript Object Notation) stores data in objects and arrays. In an object every value has a name, and an array keeps its values in a fixed order. According to RFC 8259, a JSON text can consist of any single value, for example a lone number, and a name in an object can be any string[1].

XML (Extensible Markup Language) holds data in elements with opening and closing tags. The specification from the W3C (World Wide Web Consortium) sets two conditions that matter when you convert from JSON. A document has exactly one root element, and an element name cannot start with a digit, among other characters[2].

The converter meets both conditions: it sets the root element of the document and checks every key before it writes the key as an element name.

Paste JSON into the JSON field, or click the Add JSON file link above the field and choose a file. The field accepts an object, an array or a single value. After you click Convert, the XML document appears in the XML field. The Copy button copies the result, and the Download button saves the file converted.xml.

The result starts with the declaration <?xml version="1.0" encoding="UTF-8"?>. An object key becomes the element name and its value the element content, so {"city": "Boston"} gives <city>Boston</city>. Numbers and booleans go into the element as text, which is why {"age": 30} gives <age>30</age>. An array under a key repeats the element named after that key, for example <list>1</list><list>2</list>.

A single top-level key becomes the root element. Several keys, an array or a single value go into a <root> element, because XML requires exactly one root element[2]. Entries of an array without a name of its own get <item> elements, and null gives an empty element.

A JSON key can be any string, including one with a space or with a digit at the start. An XML element name follows character rules: the XML 1.0 specification rules out a digit, a full stop and a hyphen at its start[2]. The converter replaces every disallowed character with an underscore and adds an underscore in front of a name that starts with such a character. The key "first name" therefore gives the element <first_name>, and the key "2024" gives the element <_2024>. Accented letters such as é stay unchanged, because they belong to the character ranges allowed in names.

A colon in an XML name marks a namespace prefix, and the Namespaces in XML specification requires every such prefix to be declared[3]. The converter keeps the colon when the same object or a parent object holds an @xmlns key with that prefix, for example "@xmlns:soap". In all other keys, the colon also turns into an underscore.

You write an attribute in JSON as a key with the @ prefix, and the element text as the #text key. The object {"product": {"@sku": "A-17", "name": "Lamp"}} gives the element <product sku="A-17"> with the element <name>Lamp</name> inside. The Json.NET library for .NET marks attributes the same way[4]. The XML to JSON converter produces exactly this notation, so its output turns back into XML with the same attributes.

The converter writes the characters &, <, >, quotation marks and apostrophes in values as entities, for example Smith & Sons as Smith & Sons[2]. It removes from values the control characters that XML 1.0 does not allow in a document.