The main difference
JSON represents data with objects, arrays, numbers, strings, booleans, and null. XML represents a document tree with elements, attributes, and text. JSON is often more compact for APIs, while XML remains useful where namespaces, mixed content, schemas, or document-oriented workflows matter.
Choose for the consumer
Use the format expected by the receiving system. Consider validation requirements, existing libraries, streaming behavior, human editing, and compatibility rather than choosing only by file size. Both formats can represent complex nested information.
Security and validation
Never parse untrusted content with eval. For XML, disable or reject external entity declarations to avoid entity-related attacks. For JSON, surface exact syntax errors and validate the resulting shape before using it in an application.
Convert a sample
Use JSON to XML or XML to JSON to compare the structure produced from the same data.
Open the recommended toolFinal check
Conversion is only one part of the workflow. Review the output in the system where it will be used, confirm that important details remain accurate, and keep the original source until the final version has been verified.