Is JSON faster than XML?

Usually — it is smaller and parses faster, especially in browsers, because JavaScript reads it natively.

Can JSON have comments?

Not in standard JSON. Some supersets like JSON5 or JSONC add them, but plain JSON has no comment syntax.

Which is better for APIs?

JSON for most modern web APIs. XML still appears in SOAP services and some enterprise systems that were built around it.

JSON vs XML: What's the Difference?

Published 10/20/2025 · 2 min read · Developer tools

Daniel Okonkwo — Front-end developer and tech writer at Allin

Web performance · File formats

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In short

JSON and XML both store structured data as text, but JSON is lighter and JavaScript-native while XML is more verbose and feature-rich. JSON uses key–value pairs and arrays; XML uses nested tags. For web APIs, JSON is now the default; XML still leads where documents, schemas and mixed content matter, like config files and publishing.

JSON and XML both store structured data as text, but they trade off differently. Here's how each looks, where each wins, and how to choose.

What each looks like

JSON writes data as key–value pairs: {"name": "Ada", "age": 36}. XML wraps the same data in tags: <person><name>Ada</name><age>36</age></person>. JSON's structure maps directly onto the objects and arrays of most programming languages, while XML reads more like a marked-up document, with room for attributes and nested markup.

Where JSON wins

JSON is lighter on the wire, parses natively in the browser, and turns straight into objects with one function call. That makes it the default for REST and modern web APIs, mobile apps and config where speed and simplicity matter. Less text also means less to type, less to break and faster transfers.

Where XML still leads

XML brings tools JSON lacks: schemas (XSD) to validate structure, namespaces to mix vocabularies, comments, attributes, and clean handling of mixed text and markup — exactly what documents need. It endures in publishing, office file formats, SVG, RSS, SOAP web services and plenty of enterprise and Java config, where those features earn their extra verbosity.

How to choose

Reach for JSON when you build web or mobile APIs, work in JavaScript, or just want compact data — which covers most new projects. Choose XML when you need strict validation, document-style content, or must fit an existing system that speaks it. You are never locked in: converters move data between the two whenever a boundary demands the other format.

JSON vs XML
Aspect	JSON	XML
Syntax	Key–value pairs, arrays	Nested tags
Verbosity	Compact	Heavier
Comments	No (natively)	Yes
Best for	Web APIs, config	Documents, schemas

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Frequently asked questions

Is JSON faster than XML?: Usually — it is smaller and parses faster, especially in browsers, because JavaScript reads it natively.
Can JSON have comments?: Not in standard JSON. Some supersets like JSON5 or JSONC add them, but plain JSON has no comment syntax.
Which is better for APIs?: JSON for most modern web APIs. XML still appears in SOAP services and some enterprise systems that were built around it.

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