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    3.21.0 • Public • Published


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    Validate XML, Parse XML to JS/JSON and vice versa, or parse XML to Nimn rapidly without C/C++ based libraries and no callback

    To cover expenses, we're planning to launch FXP Enterprise edition in parallel. Watch it for further updates, if you're interested.

    Donate $5

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    Check ThankYouBackers for our contributors


    List of some applications/projects using Fast XML Parser. (Raise an issue to submit yours)

    The list of users is collected either from the list published by Github, cummunicated 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.

    Main Features

    FXP logo

    • Validate XML data syntactically
    • Transform XML to JSON or Nimn
    • Transform JSON back to XML
    • Works with node packages, in browser, and in CLI (press try me button above for demo)
    • Faster than any pure JS implementation.
    • It can handle big files (tested up to 100mb).
    • Various options are available to customize the transformation
      • You can parse CDATA as a separate property.
      • You can prefix attributes or group them to a separate property. Or they can be ignored from the result completely.
      • You can parse tag's or attribute's value to primitive type: string, integer, float, hexadecimal, or boolean. And can optionally decode for HTML char.
      • You can remove namespace from tag or attribute name while parsing
      • It supports boolean attributes, if configured.

    How to use


    To use it as an NPM package:

    npm install fast-xml-parser

    Or using yarn:

    yarn add fast-xml-parser

    To use it from a CLI install it globally with the -g option.

    npm install fast-xml-parser -g

    To use it on a webpage include it from a CDN

    XML to JSON

    const jsonObj = parser.parse(xmlData [,options] );
    const parser = require('fast-xml-parser');
    const he = require('he');
    const options = {
        attributeNamePrefix : "@_",
        attrNodeName: "attr", //default is 'false'
        textNodeName : "#text",
        ignoreAttributes : true,
        ignoreNameSpace : false,
        allowBooleanAttributes : false,
        parseNodeValue : true,
        parseAttributeValue : false,
        trimValues: true,
        cdataTagName: "__cdata", //default is 'false'
        cdataPositionChar: "\\c",
        parseTrueNumberOnly: false,
          hex: true,
          leadingZeros: true,
          //skipLike: /\+[0-9]{10}/
        arrayMode: false, //"strict"
        attrValueProcessor: (val, attrName) => he.decode(val, {isAttributeValue: true}),//default is a=>a
        tagValueProcessor : (val, tagName) => he.decode(val), //default is a=>a
        stopNodes: ["parse-me-as-string"],
        alwaysCreateTextNode: false
    if( parser.validate(xmlData) === true) { //optional (it'll return an object in case it's not valid)
        let jsonObj = parser.parse(xmlData,options);
    // Intermediate obj
    const tObj = parser.getTraversalObj(xmlData,options);
    let jsonObj = parser.convertToJson(tObj,options);

    As you can notice in the above code, validator is not embedded with in the parser and expected to be called separately. However, you can pass true or validation options as 3rd parameter to the parser to trigger validator internally. It is same as above example.

      let jsonObj = parser.parse(xmlData,options, true);

    Validator returns the following object in case of error;

      err: {
        code: code,
        msg: message,
        line: lineNumber,

    Note: he library is used in this example

    • attributeNamePrefix : prepend given string to attribute name for identification
    • attrNodeName: (Valid name) Group all the attributes as properties of given name.
    • ignoreAttributes : Ignore attributes to be parsed.
    • ignoreNameSpace : Remove namespace string from tag and attribute names.
    • allowBooleanAttributes : a tag can have attributes without any value
    • parseNodeValue : Parse the value of text node to float, integer, or boolean.
    • parseAttributeValue : Parse the value of an attribute to float, integer, or boolean.
    • trimValues : trim string values of an attribute or node
    • decodeHTMLchar : This options has been removed from 3.3.4. Instead, use tagValueProcessor, and attrValueProcessor. See above example.
    • cdataTagName : If specified, parser parse CDATA as nested tag instead of adding it's value to parent tag.
    • cdataPositionChar : It'll help to covert JSON back to XML without losing CDATA position.
    • parseTrueNumberOnly: if true then values like "+123", or "0123" will not be parsed as number.
    • arrayMode : When false, a tag with single occurrence is parsed as an object but as an array in case of multiple occurences. When true, a tag will be parsed as an array always excluding leaf nodes. When strict, all the tags will be parsed as array only. When instance of RegEx, only tags will be parsed as array that match the regex. When function a tag name is passed to the callback that can be checked.
    • tagValueProcessor : Process tag value during transformation. Like HTML decoding, word capitalization, etc. Applicable in case of string only.
    • attrValueProcessor : Process attribute value during transformation. Like HTML decoding, word capitalization, etc. Applicable in case of string only.
    • stopNodes : an array of tag names which are not required to be parsed. Instead their values are parsed as string.
    • alwaysCreateTextNode : When true, forces the parser always return a property for the textNodeName even if there are no attributes or node children.
    To use from command line
    $xml2js [-ns|-a|-c|-v|-V] <filename> [-o outputfile.json]
    $cat xmlfile.xml | xml2js [-ns|-a|-c|-v|-V] [-o outputfile.json]
    • -ns : To include namespaces (by default ignored)
    • -a : To ignore attributes
    • -c : To ignore value conversion (i.e. "-3" will not be converted to number -3)
    • -v : validate before parsing
    • -V : only validate
    To use it on webpage
    const result = parser.validate(xmlData);
    if (result !== true) console.log(result.err);
    const jsonObj = parser.parse(xmlData);

    JSON / JS Object to XML

    const Parser = require("fast-xml-parser").j2xParser;
    //default options need not to set
    const defaultOptions = {
        attributeNamePrefix : "@_",
        attrNodeName: "@", //default is false
        textNodeName : "#text",
        ignoreAttributes : true,
        cdataTagName: "__cdata", //default is false
        cdataPositionChar: "\\c",
        format: false,
        indentBy: "  ",
        supressEmptyNode: false,
        tagValueProcessor: a=> he.encode(a, { useNamedReferences: true}),// default is a=>a
        attrValueProcessor: a=> he.encode(a, {isAttributeValue: isAttribute, useNamedReferences: true}),// default is a=>a
        rootNodeName: "element"
    const parser = new Parser(defaultOptions);
    const xml = parser.parse(json_or_js_obj);

    With the correct options, you can get the almost original XML without losing any information.

    • attributeNamePrefix : Identify attributes with this prefix otherwise treat them as a tag.
    • attrNodeName: Identify attributes when they are grouped under single property.
    • ignoreAttributes : Don't check for attributes. Treats everything as tag.
    • encodeHTMLchar : This option has been removed from 3.3.4. Use tagValueProcessor, and attrValueProcessor instead. See above example.
    • cdataTagName : If specified, parse matching tag as CDATA
    • cdataPositionChar : Identify the position where CDATA tag should be placed. If it is blank then CDATA will be added in the last of tag's value.
    • format : If set to true, then format the XML output.
    • indentBy : indent by this char when format is set to true
    • supressEmptyNode : If set to true, tags with no value (text or nested tags) are written as self closing tags.
    • tagValueProcessor : Process tag value during transformation. Like HTML encoding, word capitalization, etc. Applicable in case of string only.
    • attrValueProcessor : Process attribute value during transformation. Like HTML encoding, word capitalization, etc. Applicable in case of string only.
    • rootNodeName : When input js object is array, parser uses array index by default as tag name. You can set this property for proper response.


    XML to JSON


    file size fxp 3.0 validator (rps) fxp 3.0 parser (rps) xml2js 0.4.19 (rps)
    1.5k 16581.06758 14032.09323 4615.930805
    1.5m 14918.47793 13.23366098 5.90682005
    13m 1.834479235 1.135582008 -1
    1.3k with CDATA 30583.35319 43160.52342 8398.556349
    1.3m with CDATA 27.29266471 52.68877009 7.966000795
    1.6k with cdata,prolog,doctype 27690.26082 41433.98547 7872.399268
    98m 0.08473858148 0.2600104004 -1
    • -1 indicates error or incorrect output.

    JSON to XML


    file size fxp 3.2 js to xml xml2js 0.4.19 builder
    1.3k 160148.9801 10384.99401
    1.1m 173.6374831 8.611884025

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    • MIT License


    npm i fast-xml-parser

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    • amitgupta