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😜⌨ URLCrazy

URLCrazy is an OSINT tool to generate and test domain typos or variations to detect or perform typo squatting, URL hijacking, phishing, and corporate espionage.


🌟 Use Cases

  • Detect typo squatters profiting from typos on your domain name
  • Protect your brand by registering popular typos
  • Identify typo domain names that will receive traffic intended for another domain
  • Conduct phishing attacks during a penetration test

⭐ Features

  • Generates 15 types of domain variants
  • Knows over 8000 common misspellings
  • Over 1500 Top Level Domains supported
  • Bit-flipping attacks
  • Multiple keyboard layouts (QWERTY, AZERTY, QWERTY, DVORAK)
  • Checks if a domain variant is valid
  • Test if domain variants are in use
  • Estimate popularity of a domain variant

πŸ›  Installation

Install from a package manager

If you are using Kali Linux, Ubuntu or Debian use:

$ sudo apt install urlcrazy

Install latest release


Install current development version

Be aware the latest development version may not be stable.

$ git clone

Install Ruby

URLCrazy has been tested with Ruby versions 2.4 and 2.6.

If you are using Ubuntu or Debian use:

$ sudo apt install ruby

Install Bundler

Bundler provides dependecy management for Ruby projects

$ gem install bundler

Install Dependencies

$ bundle install

Alternatively, if you don't want to install bundler, the following command will install the gem dependencies.

$ gem install json colorize async async-dns async-http

πŸ’» Usage


Simple Usage

With default options, URLCrazy will check over 2000 typo variants for

$ urlcrazy


With popularity estimate

$ urlcrazy -p

Commandline Usage

db    db d8888b. db       .o88b. d8888b.  .d8b.  d88888D db    db
88    88 88  `8D 88      d8P  Y8 88  `8D d8' `8b YP  d8' `8b  d8'
88    88 88oobY' 88      8P      88oobY' 88ooo88    d8'   `8bd8'
88    88 88`8b   88      8b      88`8b   88~~~88   d8'      88
88b  d88 88 `88. 88booo. Y8b  d8 88 `88. 88   88  d8' db    88
~Y8888P' 88   YD Y88888P  `Y88P' 88   YD YP   YP d88888P    YP

URLCrazy version 0.7.3 by Andrew Horton (urbanadventurer)

Generate and test domain typos and variations to detect and perform typo squatting, URL hijacking,
phishing, and corporate espionage.

Supports the following domain variations:
Character omission, character repeat, adjacent character swap, adjacent character replacement, double
character replacement, adjacent character insertion, missing dot, strip dashes, insert dash,
singular or pluralise, common misspellings, vowel swaps, homophones, bit flipping (cosmic rays),
homoglyphs, wrong top level domain, and wrong second level domain.

Usage: ./urlcrazy [options] domain

-k, --keyboard=LAYOUT  Options are: qwerty, azerty, qwertz, dvorak (default: qwerty)
-p, --popularity       Check domain popularity with Google
-r, --no-resolve       Do not resolve DNS
-i, --show-invalid     Show invalid domain names
-f, --format=TYPE      Human readable, JSON, or CSV (default: human readable)
-o, --output=FILE      Output file
-n, --nocolor          Disable colour
-d, --debug            Enable debugging output for development
-h, --help             This help
-v, --version          Print version information. This version is 0.7.3

πŸ”¦ Types of Domain Variations Supported

Character Omission

These typos are created by leaving out a letter of the domain name, one letter at a time. For example, and

Character Repeat

These typos are created by repeating a letter of the domain name. For example, and

Adjacent Character Swap

These typos are created by swapping the order of adjacent letters in the domain name. For example, and

Adjacent Character Replacement

These typos are created by replacing each letter of the domain name with letters to the immediate left and right on the keyboard. For example, and

Double Character Replacement

These typos are created by replacing identical, consecutive letters of the domain name with letters to the immediate left and right on the keyboard. For example, and

Adjacent Character Insertion

These typos are created by inserting letters to the immediate left and right on the keyboard of each letter. For example, and

Missing Dot

These typos are created by omitting a dot from the domainname. For example, and www.googlecom

Strip Dashes

These typos are created by omitting a dash from the domainname. For example, becomes

Singular or Pluralise

These typos are created by making a singular domain plural and vice versa. For example, becomes and becomes

Common Misspellings

Over 8000 common misspellings from Wikipedia. For example, becomes and becomes

Vowel Swapping

Swap vowels within the domain name except for the first letter. For example, becomes


Over 450 sets of words that sound the same when spoken. For example, becomes

Bit Flipping

Each letter in a domain name is an 8bit character. The character is substituted with the set of valid characters that can be made after a single bit flip. For example, becomes,,,,, etc.


One or more characters that look similar to another character but are different are called homogylphs. An example is that the lower case l looks similar to the numeral one, e.g. l vs 1. For example, becomes

Wrong Top Level Domain

For example, becomes and becomes Uses the 19 most common top level domains.

Wrong Second Level Domain

Uses an alternate, valid second level domain for the top level domain. For example, becomes and

⌨ Supported Keyboard Layouts

Keyboard layouts supported are:


πŸ•― Is the domain valid?

URLCrazy has a database of valid top level and second level domains. This information has been compiled from Wikipedia and domain registrars. We know whether a domain is valid by checking if it matches top level and second level domains. For example, is a valid domain in Belize which allows any second level domain registrations but isn't because isn't an allowed second level domain in New Zealand.

πŸ’‘ Popularity Estimate

URLCrazy pioneered the technique of estimating the relative popularity of a typo from search engine results data. By measuring how many times a typo appears in webpages, we can estimate how popular that typo will be made when users type in a URL.

The inherent limitation of this technique, is that a typo for one domain, can be a legitimate domain in its own right. For example, is a typo of but it also a legitimate domain.

For example, consider the following typos for

Count. Typo

πŸ”§ Troubleshooting

MacOS File Descriptor Limit

If DNS resolution fails under Macos it could be due to the small default file descriptor limit.

To display the current file descriptor limit use:

$ ulimit -a

To increase the file descriptor limit use:

$ ulimit -n 10000

No results for Wrong TLDs

Check your ulimit and set it to 10000 or a number higher than number of hostnames you are processing.

πŸ’£ Known Issues

No WHOIS checking

This tool does not check if a domain has been registered. This is due to WHOIS servers enforcing rate-limiting and banning IP addresses.

πŸ‘ URLCrazy Appearances

Kali Linux

URLCrazy was a default tool in BackTrack 5, and later Kali Linux.

The Browser Hacker's Handbook

Authored by Wade Alcorn, Christian Frichot, and Michele Orru.

URLCrazy is included in Chapter 2 of this seminal work on the topic.

PTES Technical Guidelines

Penetration Testing Execution Standard (PTES) is a standard designed to provide a common language and scope for performing penetration testing (i.e. Security evaluations). URLCrazy is included in the Tools Required section.

Network Security Toolkit

Network Security Toolkit is a bootable Linux distribution designed to provide easy access to best-of-breed Open Source Network Security Applications.

πŸ“š Other Projects

URLCrazy was first published in 2009, and for many years was the most advanced opensource tool for studying typosquatting. Since then multiple other tools have been developed by the infosec community.


DNSTwist is developed by Marcin Ulikowski and first published in 2015. DNSTwist had a significant feature overlap with URLCrazy at the time, and introduced many new features.

Language: Python


URLInsane was developed by Rangertaha in 2018 and claims to match the features of URLCrazy and DNSTwist.

Language: Go


DomainFuzz was developed by monkeym4sterin 2017. Language: Node.JS

😎 Authors and Acknowledgement

Developed by Andrew Horton (@urbanadventurer).

  • Thanks to Ruby on Rails for Inflector which allows plural and singular permutations.
  • Thanks to Wikipedia for the set of common misspellings, homophones, and homoglyphs.
  • Thanks to for their IP to country database

πŸ™‹ Community

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Please make sure to update tests as appropriate.

πŸ“„ License

Copyright Andrew Horton, 2012-2021. You have permission to use and distribute this software. You do not have permission to distribute modified versions without permission. You do not have permission to use this as part of a commercial service unless it forms part of a penetration testing service. For example a commercial service that provides domain protection for clients must obtain a license first. Email me if you require a license.