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Random.org logo 2009-10-23.png
Random.org screenshot 2009-10-23.png
Random.org as of October, 2009
Web address Random.org
Type of site
Web service
Registration optional
Available in English
Owner Mads Haahr
Created by Mads Haahr
Launched 1998
Alexa rank
negative increase 6,515 (April 2014)[1]
Current status online

Random.org is a website that produces "true" random numbers based on atmospheric noise.[2] In addition to generating random numbers in a specified range and subject to a specified probability distribution, it has free tools to simulate events such as flipping coins, shuffling cards, and rolling dice. It also offers paid services to generate longer sequences of random numbers and act as a third-party arbiter for raffles, sweepstakes, and promotions.

The website was created in 1998 by Mads Haahr,[3][4] a doctor and computer science professor at Trinity College in Dublin, Ireland. Random numbers are generated based on atmospheric noise captured by several radios tuned between stations.[5][6]


A binary digit (bit) can be either 0 or 1. There are several Random.org radios at different locations each generating 3,000 bits per second from the atmospheric noise picked up.[7] The generators produce a continuous string of random bits which are converted into the form requested (integer, Gaussian distribution, etc.)


There are limits to the number of bits supplied to a particular IP address. A new user (identified by IP address) starts with a free-of-charge quota of 1,000,000 bits which is depleted every time bits are supplied, and topped up by 200,000 bits (or to 1,000,000 bits if less) every day at midnight UTC. Larger number of bits can be purchased for US$10 for 10 million bits with no time limit, less per bit for larger quantities.[8]


  1. ^ "Random.org Site Info". Alexa Internet. Retrieved 2014-04-01. 
  2. ^ O'Connell, Pamela LiCalzi (2004-04-08). "Lottery Numbers and Books With a Voice". New York Times. Retrieved 2009-10-23. Other sites also offer true random numbers, said Mads Haahr, lecturer in computer science at Trinity College, Dublin [dead link]
  3. ^ McNichol, Tom (2003-08-11). "Totally Random". Conde Nast Publications. p. 2. Retrieved 2009-10-23. Mads Haahr, a lecturer in computer science at Trinity College in Dublin, designed the system 
  4. ^ Klarreich, Erica (2004-12-04). "Take a chance: scientists put randomness to work". Science News. Archived from the original on 2009-10-23. Haahr's Web site (//www.random.org/) can generate up to 3,000 random numbers per second 
  5. ^ Johnson, George (2001-06-12). "Connoisseurs of Chaos Offer A Valuable Product: Randomness". New York Times. Retrieved 2009-10-23. Random.org generates unpredictable sequences of data using a radio tuned between stations, harvesting the atmospheric noise 
  6. ^ Bialik, Carl (2009-10-14). "How Random Is the iPod's Shuffle?". Wall Street Journal. Retrieved 2009-10-23. 
  7. ^ random.org: History
  8. ^ "Your Quota". Random.org. Retrieved 2011-10-30. 

External links[edit]