JSON (JavaScript Object Notation) and XML (eXtensible Markup Language) are both text formats for structured data. They differ in syntax, verbosity, schema ecosystems, and where each is still the default choice.
This guide compares them at a high level, shows the same logical record in both formats, and outlines readability, usage, and parsing trade‑offs.
JSON is a minimal, language‑independent format derived from JavaScript literal syntax. It is the dominant choice for REST and GraphQL payloads, browser fetch, and many mobile clients because it maps cleanly to objects and arrays in modern languages.
Objects { }, arrays [ ], strings, numbers, booleans, and null cover almost every API contract.
Same data is usually smaller on the wire than verbose XML with repeated tag names.
JSON.parse / JSON.stringify are built into browsers and Node.js; other stacks ship fast native parsers.
XML describes tree‑shaped data with nested elements, optional attributes, and namespaces. It is still common in enterprise integration, SOAP, configuration (for example Spring XML), RSS/Atom, and document formats where mixed content matters.
Clear parent/child boundaries; attributes hang on elements without extra nesting.
Vocabularies combine via namespaces; XSD and related tooling mature in regulated industries.
Long history in B2B, publishing, and standards bodies—interop with legacy systems is a strength.
Below is one small person record expressed as JSON and as XML. In XML, false is plain text inside the element; your schema or code decides how to interpret it.
{
"name": "John",
"age": 30,
"isStudent": false,
"hobbies": ["reading", "traveling", "photography"]
}<person>
<name>John</name>
<age>30</age>
<isStudent>false</isStudent>
<hobbies>
<hobby>reading</hobby>
<hobby>traveling</hobby>
<hobby>photography</hobby>
</hobbies>
</person>The same data can feel different in the editor depending on whether you prefer brace syntax or explicit open/close tags.
Usually faster to scan if you live in C‑style languages: { }, [ ], and quoted keys keep shallow API payloads visually compact.
More lines on the page, but matching <open> / </close> pairs can make deep trees easier to follow with indentation and a good highlighter.
Where each format is still the default in real systems—not which one is “newer,” but which toolchain expects which shape.
First choice for browser and mobile clients talking to HTTP JSON APIs.
Still the lingua franca where WSDL, XSD, or document specs are already baked in.
Both formats are mature; the difference is how much machinery you need for validation and transformation after the bytes arrive.
Tiny grammar: most runtimes ship a fast parser and a single call turns text into native maps and lists.
JSON.parse / JSON.stringify in JavaScriptPull, DOM, and SAX parsers are everywhere; you often layer XSD validation, XPath queries, or XSLT on top.
Choose JSON for most HTTP APIs and browser‑first stacks; payloads are smaller and map directly to native types.
Choose XML when you need namespaces, attributes alongside children, XSD workflows, or existing enterprise contracts.
Neither format is “wrong”—match the ecosystem (clients, validators, regulations) your team operates in.
link.rel), parallel keys such as linkHref, or a small convention documented in your API design guide.Learn the exact punctuation rules so every parser accepts your documents.
JSON has no built‑in attributes or namespaces; everything is keys and values in a tree. XML can attach metadata on tags (id=, xmlns:) and is still common where schemas, signatures, and enterprise tooling expect angle‑bracket documents.
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