URLCrazy : OSINT Tool To Generate And Test Domain

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


  • Generates 15 types of domain variants
  • Knows over 8000 common misspellings
  • Supports bit flipping attacks
  • Multiple keyboard layouts (qwerty, azerty, qwertz, dvorak)
  • Checks if a domain variant is valid
  • Test if domain variants are in use
  • Estimate popularity of a domain variant


  • 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

Also Read – DroidFiles : Get Files From Android Directories


  • Simple Usage

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

$ urlcrazy

  • With popularity estimate

$ urlcrazy -p

  • Commandline Usage

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 or CSV (default: human readable)
-o, –output=FILE Output file
-n, –nocolor Disable colour
-h, –help This help
-v, –version Print version information. This version is 0.7

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
  • Adjacent Character Swap
  • 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
  • Singular or Pluralise
  • Common Misspellings
  • Vowel Swapping
  • Homophones
  • 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.
  • Homoglyphs
    • 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
  • Wrong Second Level Domain

Supported Keyboard Layouts

Keyboard layouts supported are:


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.

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


Known Issues

  • 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

URLCrazy Appearances

  • 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.

See Also

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