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    DefinitelyTyped icon, indicating that this package has TypeScript declarations provided by the separate @types/uid-generator package

    2.0.0 • Public • Published


    NPM Version Build Status Coverage Status devDependency Status

    Generates cryptographically strong, pseudo-random UIDs with custom size and base-encoding. Generated UIDs are strings that are guaranteed to always be the same length depending on the specified bit-size.

    Great for generating things like compact API keys and UIDs that are safe to use in URLs and cookies.

    Tip: The main benefit of this module is the ability to easily generate human-safe UIDs (using base58) and large UIDs that are more compact (using something like base94). If you’re just looking to generate URL-safe base64 IDs, the best package for that is uid-safe.


    npm install uid-generator --save
    # or 
    yarn add uid-generator


    const UIDGenerator = require('uid-generator');
    const uidgen = new UIDGenerator(); // Default is a 128-bit UID encoded in base58
    // Async with `await`
    await uidgen.generate(); // -> 'B1q2hUEKmeVp9zWepx9cnp'
    // Async with promise
      .then(uid => console.log(uid)); // -> 'PXmRJVrtzFAHsxjs7voD5R'
    // Async with callback
    uidgen.generate((err, uid) => {
      if (err) throw err;
      console.log(uid); // -> '4QhmRwHwwrgFqXULXNtx4d'
    // Sync
    uidgen.generateSync(); // -> '8Vw3bgbMMzeYfrQHQ8p3Jr'


    new UIDGenerator([bitSize][, baseEncoding])

    Creates a new UIDGenerator instance that generates bitSize-bit or uidLength-sized UIDs encoded using the characters in baseEncoding.

    Param Type Default Description
    [bitSize] number 128 The size of the UID to generate in bits. Must be a multiple of 8.
    [baseEncoding] string UIDGenerator.BASE58 One of the UIDGenerator.BASE## constants or a custom string of characters to use to encode the UID.

    Note: If a custom baseEncoding that has URL-unsafe characters is used, it is up to you to URL-encode the resulting UID.


    new UIDGenerator();
    new UIDGenerator(256);
    new UIDGenerator(UIDGenerator.BASE16);
    new UIDGenerator(512, UIDGenerator.BASE62);
    new UIDGenerator('01'); // Custom encoding (base2)

    uidgen.generate([cb]) ⇒ ?Promise<string>

    Asynchronously generates a UID.

    Param Type Description
    [cb] ?function(error, uid) An optional callback that will be called with the results of generating the UID.
    If not specified, the function will return a promise.

    Returns: ?Promise<string> - A promise that will resolve with the UID or reject with an error. Returns nothing if the cb parameter is specified.

    async/await Example

    const uidgen = new UIDGenerator();
    // This must be inside an async function
    const uid = await uidgen.generate();

    Promise Example

    const uidgen = new UIDGenerator();
      .then(uid => {
        // Use uid here

    Callback Example

    const uidgen = new UIDGenerator();
    uidgen.generate((err, uid) => {
      if (err) throw err;
      // Use uid here

    uidgen.generateSync() ⇒ string

    Synchronously generates a UID.

    Returns: string - The generated UID.


    const uidgen = new UIDGenerator();
    const uid = uidgen.generateSync();

    (readonly) uidgen.bitSize : number

    The size of the UID that will be generated in bits (the bitSize value passed to the UIDGenerator constructor). If the uidLength parameter is passed to the constructor instead of bitSize, bitSize is calculated as follows:

    bitSize = Math.ceil(length * Math.log2(base));


    new UIDGenerator().bitSize // -> 128
    new UIDGenerator(256).bitSize // -> 256

    (readonly) uidgen.uidLength : number

    The length of the UID string that will be generated. The generated UID will always be this length. This will be the same as the uidLength parameter passed to the UIDGenerator constructor. If the uidLength parameter is not passed to the constructor, it will be calculated using the bitSize parameter as follows:

    uidLength = Math.ceil(bitSize / Math.log2(base))


    new UIDGenerator().uidLength // -> 22
    new UIDGenerator(256, UIDGenerator.BASE62).uidLength // -> 43

    (readonly) uidgen.baseEncoding : string

    The set of characters used to encode the UID string (the baseEncoding value passed to the UIDGenerator constructor).


    new UIDGenerator().baseEncoding // -> '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'
    new UIDGenerator(UIDGenerator.BASE16).baseEncoding // -> '0123456789abcdef'
    new UIDGenerator('01').baseEncoding // -> '01'

    (readonly) uidgen.base : number

    The base of the UID that will be generated (which is the number of characters in the baseEncoding).


    new UIDGenerator().base // -> 58
    new UIDGenerator(UIDGenerator.BASE16).base // -> 16
    new UIDGenerator('01').base // -> 2

    UIDGenerator.BASE16 : string


    UIDGenerator.BASE36 : string


    UIDGenerator.BASE58 : string


    (all alphanumeric characters except for 0, O, I, and l — characters easily mistaken for each other)

    The default base.

    Tip: Use this base to create UIDs that are easy to type in manually.

    UIDGenerator.BASE62 : string


    UIDGenerator.BASE66 : string


    (all ASCII characters that do not need to be encoded in a URI as specified by RFC 3986)

    UIDGenerator.BASE71 : string


    (all ASCII characters that are not encoded by encodeURIComponent())

    UIDGenerator.BASE94 : string


    (all readable ASCII characters)


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