Amazingly short non-sequential url-friendly unique id generator.


Amazingly short non-sequential url-friendly unique id generator.

ShortId creates amazingly short non-sequential url-friendly unique ids. Perfect for url shorteners, MongoDB and Reddis ids, and any other id users might see.

  • By default 7-14 url-friendly characters: A-Z, a-z, 0-9, _-
  • Non-sequential so they are not predictable.
  • Supports cluster (automatically), custom seeds, custom alphabet.
  • Can generate any number of ids without duplicates, even millions per day.
  • Perfect for games, especially if you are concerned about cheating so you don't want an easily guessable id.
  • Apps can be restarted any number of times without any chance of repeating an id.
  • Popular replacement for Mongo ID/Mongoose ID.
  • Works in Node, io.js, and web browsers.
  • Includes Mocha tests.
var shortid = require('shortid');

Mongoose Unique Id

_id: {
    type: String,
    unique: true,
    'default': shortid.generate

The best way to use shortid in the browser is via browserify or webpack.

These tools will automatically only include the files necessary for browser compatibility.

All tests will run in the browser as well:

## build the bundle, then open Mocha in a browser to see the tests run.
$ grunt build open
~/projects/shortid ❯ node examples/examples.js

shortId was created for Node Knockout 2011 winner for Most Fun Doodle Or Die. Millions of doodles have been saved with shortId filenames. Every log message gets a shortId to make it easy for us to look up later.

Here are some other projects that use shortId:

  • bevy - A simple server to manage multiple Node services.
  • capre - Cross-Server Data Replication.
  • cordova-build - an alternative to phonegap build that runs on your servers/agents.
  • couchdb-tools - A library of handy functions for use when working with CouchDB documents.
  • CleverStack/clever-email - E-mail system for CleverStack.
  • CloudTypes - JavaScript end2end implementation of the Cloud Types model for Eventual Consistency programming.
  • dnode-tarantula - an asynchronous rpc and event system for node.js based on dnode-protocol and TCP sockets.
  • mongoose-url-shortener - A simple URL Shortening library for NodeJS using Promises/A+ results.
  • mozilla/smokejumper - The Smoke Jumper project is an effort to bring dead simple, secure, P2P file sharing to Firefox.
  • shortness - Node based URL shortener that uses SQLite.
  • file-db - Document database that uses directories and files to store its data, supporting nested key-value objects in named collections.
  • resume-generator - Resume Generator.
  • riffmint - Collaboration in musical space.
  • rap1ds/dippa - Dippa Editor – A web-based LaTeX editor

var shortid = require('shortid');

Returns string non-sequential unique id.


    _id: shortid.generate()
    name: ...
    email: ...

Default: '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-_'

Returns new alphabet as a string

Recommendation: If you don't like _ or -, you can to set new characters to use.


Change the characters used.

You must provide a string of all 64 unique characters. Order is not important.

The default characters provided were selected because they are url safe.


// use $ and @ instead of - and _ 
// any 64 unicode characters work, but I wouldn't recommend this. 

Returns boolean

Check to see if an id is a valid shortid. Note: This only means the id could have been generated by shortid, it doesn't guarantee it.


// true 
shortid.isValid('i have spaces');
// false 

Default: process.env.NODE_UNIQUE_ID || 0

Recommendation: You typically won't want to change this.


If you are running multiple server processes then you should make sure every one has a unique worker id. Should be an integer between 0 and 16. If you do not do this there is very little chance of two servers generating the same id, but it is theatrically possible if both are generated in the exact same second and are generating the same number of ids that second and a half-dozen random numbers are all exactly the same.



Default: 1

Recommendation: You typically won't want to change this.


Choose a unique value that will seed the random number generator so users won't be able to figure out the pattern of the unique ids. Call it just once in your application before using shortId and always use the same value in your application.

Most developers won't need to use this, it's mainly for testing ShortId.

If you are worried about users somehow decrypting the id then use it as a secret value for increased encryption.



Hi! Thanks for checking out this project! My name is Dylan Greene. When not overwhelmed with my two young kids I enjoy contributing to the open source community. I'm also a tech lead at Opower.

Here's some of my other Node projects:

NameDescriptionnpm Downloads
grunt‑notifyAutomatic desktop notifications for Grunt errors and warnings using Growl for OS X or Windows, Mountain Lion and Mavericks Notification Center, and Notify-Send.
npm‑checkCheck for outdated, incorrect, and unused dependencies.
grunt‑promptInteractive prompt for your Grunt config using console checkboxes, text input with filtering, password fields.
rssRSS feed generator. Add RSS feeds to any project. Supports enclosures and GeoRSS.
xmlFast and simple xml generator. Supports attributes, CDATA, etc. Includes tests and examples.
changelogCommand line tool (and Node module) that generates a changelog in color output, markdown, or json for modules in's registry as well as any public repo.
grunt‑attentionDisplay attention-grabbing messages in the terminal
observatoryBeautiful UI for showing tasks running on the command line.
anthologyModule information and stats for any @npmjs user
grunt‑catEcho a file to the terminal. Works with text, figlets, ascii art, and full-color ansi.

This list was generated using anthology.

Copyright (c) 2015 Dylan Greene, contributors.

Released under the MIT license.

Screenshots are CC BY-SA (Attribution-ShareAlike).

Generated using grunt-readme with grunt-templates-dylang on Sunday, April 5, 2015. _To make changes to this document look in /templates/readme/