Schema aware compression of JS object/JSON data. 60% more compressed than json

Usage no npm install needed!

<script type="module">
  import nimnjs from '';



JS implementation of nimn specification. Highly Compressed JS object/JSON. 60% or more compressed than JSON, 40% or more compressed than msgpack

Known Vulnerabilities Travis ci Build Status Coverage Status Try me Twitter URL

Become a Patron! Stubmatic donate button


NIMN JS can parse JS object to nimn data and vice versa. See Nimn specification for more detail.


First install or add to your npm package

$npm install nimnjs
var nimn = require("nimnjs");

var objStructure = {
    type : "list",
    detail : {
        type : "map",
        detail : [{
            name : "name",
            type : "string"
            name : "age",
            type : "number"
            name : "isHuman",
            type : "boolean"
            name : "address",
            type : "string"
            name : "hobbies",
            type : "list",
            detail : {
                type : "string"
            name : "project",
            type : "map",
            detail: [{
                name: "title",
                type : "string"
                name: "description",
                type : "string"
                name: "status",
                type : "string"

var schema = nimn.buildSchema(objStructure);

var jData = [{
    "name" : "somename",
    "isHuman" : true,
    "age": 32,
    "address" : "I'll not tell you",
    hobbies : [ 
        , "not reading "+ parser.chars.missingPremitive +" book"
        , "watching \\"+ parser.chars.nilPremitive +" movie"
    project : {
        title : "nimn",
        //description : "it is 80% smaller",
        status : "rocking"

var nimnDataString = nimn.stringify(schema, jData);
var result = nimn.parse(schema, nimnDataString);


  • You can use old schema to parse nimn data created with old or new schema.
  • You can use new schema to parse nimn data created with old or new schema.

Note that the fields must be added or deleted in the end of the map (object)

  • Fields name can be chaged in the schema used for encoding and decoding. But their type and order must not be changed.

Supported type

  • map : Fixed key value pairs
  • varmap : Variable key value pairs where the values of any key have same structure
  • list : list of similar values
  • boolean : true / false
  • string : Any valid string
  • number : Any valid number

Include dist in your HTML to use it in browser.

Check the demo for instant use. It generates schema automatically with the help of schema builder when sample json is provided.


Join the official organization on github to support it. It can not only save bandwidth but speed up communication, search and much more.


List of applications and projects using Nimn. (Raise an issue to submit yours)

Worth to mention

  • imglab : Web based tool to label images for object. So that they can be used to train dlib or other object detectors. You can integrate 3rd party libraries for fast labeling.

  • अनुमार्गक (anumargak) : The fastest router for node web servers.

  • Stubmatic : A stub server to mock behaviour of HTTP(s) / REST / SOAP services.

  • fastify-xml-body-parser : Fastify plugin / module to parse XML payload / body into JS object using fast-xml-parser.

  • fast-lorem-ipsum : Generate lorem ipsum words, sentences, paragraph very quickly.

  • Grapes : Flexible Regular expression engine which can be applied on char stream. (under development)

  • fast XML Parser : Fastest pure js XML parser for xml to js/json and vice versa. And XML validation.