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Validate XML, Parse XML, Build XML without C/C++ based libraries


Version published
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Package description

What is fast-xml-parser?

The fast-xml-parser npm package is a fast and powerful XML parser and validator that can convert XML to a JavaScript object, JSON, or a traversable JS object. It can also convert a JS object to XML. It is designed to be very fast and efficient, and it provides various options to control the XML parsing and validation process.

What are fast-xml-parser's main functionalities?

XML to JSON Conversion

Converts XML data to a JSON object. The 'parse' function takes an XML string and optional options object, and returns a JSON representation of the XML.

const { parse } = require('fast-xml-parser');
const xmlData = '<note><to>User</to><from>Library</from><heading>Reminder</heading><body>Don't forget to subscribe.</body></note>';
const options = {};
const jsonObj = parse(xmlData, options);

JSON to XML Conversion

Converts a JSON object to an XML string. The 'j2xParser' constructor takes an options object, and the 'parse' method converts the JSON object to an XML string.

const { j2xParser } = require('fast-xml-parser');
const parser = new j2xParser({});
const jsonObj = { note: { to: 'User', from: 'Library', heading: 'Reminder', body: 'Don't forget to subscribe.' } };
const xmlData = parser.parse(jsonObj);

XML Validation

Validates the XML string. The 'validate' function checks if the given XML string is well-formed and returns a validation result.

const { validate } = require('fast-xml-parser');
const xmlData = '<note><to>User</to><from>Library</from></note>';
const validationResult = validate(xmlData);

Traversable Object Creation

Creates a traversable JavaScript object from XML. The 'XMLParser' constructor creates a parser instance, and the 'parse' method converts the XML string into a traversable JS object.

const { XMLParser } = require('fast-xml-parser');
const xmlData = '<note><to>User</to><from>Library</from></note>';
const parser = new XMLParser();
const traversableObject = parser.parse(xmlData);

Other packages similar to fast-xml-parser




Known Vulnerabilities NPM quality Coverage Status Try me NPM total downloads

Validate XML, Parse XML to JS Object, or Build XML from JS Object without C/C++ based libraries and no callback.

XML Parser v5 is added for experimental use

Sponsor this project 👉 Stubmatic donate button

Current Sponsors

Check the complete list at ThankYouBackers for our sponsors and supporters.

Through Github

Through OpenCollective


Check the bigger list

The list of users is collected either from the list published by Github, communicated directly through mails/chat , or from other resources. If you feel that your name in the above list is incorrectly published or you're not the user of this library anymore then you can inform us to remove it. We'll do the necessary changes ASAP.

If you want to be an anonymous user of this application and don't want to be highlighted anywhere then you can contact me at

Main Features

FXP logo
  • Validate XML data syntactically
  • Parse XML to JS Object
  • Build XML from JS Object
  • Works with node packages, in browser, and in CLI (press try me button above for demo)
  • Faster than any other pure JS implementation.
  • It can handle big files (tested up to 100mb).
  • Controlled parsing using various options
  • XML Entities, HTML entities, and DOCTYPE entites are supported.
  • unpaired tags (Eg <br> in HTML), stop nodes (Eg <script> in HTML) are supported.
  • You can restore almost same XML from JSON
  • Supports comments
  • It can preserve Order of tags in JS object
  • You can control if a single tag should be parsed into array.
  • Supports parsing of PI (Processing Instruction) tags with XML declaration tags
  • And many more other features.


I developed v5 in Apr 2023. And I didn't get the chance to complete all the features. I've ensured that new features don't impact performance. With v5, you have more control on parsing output. Check docs for syntax help and basic understanding.

Please leave a comment in discussion forum for your suggestions and if you really need v5.

How to use

To use as package dependency $ npm install fast-xml-parser or $ yarn add fast-xml-parser

To use as system command $ npm install fast-xml-parser -g

To use it on a webpage include it from a CDN


As CLI command

$ fxparser some.xml

In a node js project

const { XMLParser, XMLBuilder, XMLValidator} = require("fast-xml-parser");

const parser = new XMLParser();
let jObj = parser.parse(XMLdata);

const builder = new XMLBuilder();
const xmlContent =;

In a HTML page

<script src="path/to/fxp.min.js"></script>
  const parser = new fxparser.XMLParser();

Check lib folder for different browser bundles

Bundle NameSize




  2. XML Parser
  3. XML Builder
  4. XML Validator
  5. Entities
  6. HTML Document Parsing
  7. PI Tag processing


XML Parser

  • Y-axis: requests per second
  • X-axis: File size

Large files

  • Y-axis: requests per second
  • X-axis: File size

XML Builder

  • Y-axis: requests per second

negative means error



This project exists thanks to all the people who contribute. [Contribute].


Thank you to all our backers! 🙏 [Become a backer]


  • MIT License

Donate $5



Last updated on 24 Feb 2024

Did you know?

Socket installs a GitHub app to automatically flag issues on every pull request and report the health of your dependencies. Find out what is inside your node modules and prevent malicious activity before you update the dependencies.


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