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Random.org as of October, 2009
Type of site
Web service
Available inEnglish
OwnerMads Haahr
Created byMads Haahr
Current statusonline

Random.org (stylized as RANDOM.ORG) is a website that produces random numbers based on atmospheric noise.[1] In addition to generating random numbers in a specified range and subject to a specified probability distribution, which is the most commonly done activity on the site, 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. Random.org is distinguished from pseudo-random number generators, which use mathematical formulae to produce random-appearing numbers.[2][3]

The website was created in 1998 by Mads Haahr,[4][5] 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.[6][7]


A binary digit (bit) can be either 0 or 1. There are several Random.org radios located in Copenhagen, Dublin, and Ballsbridge, each generating 12,000 bits per second[8] from the atmospheric noise picked up.[9] 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 the user has more than 800,000 bits remaining) every day at midnight UTC. Larger numbers of bits can be purchased.[10]


  1. ^ O'Connell, Pamela LiCalzi (8 April 2004). "Lottery Numbers and Books With a Voice". New York Times. Archived from the original on 26 July 2009. Retrieved 23 October 2009. Other sites also offer true random numbers, said Mads Haahr, lecturer in computer science at Trinity College, Dublin
  2. ^ Kassner, Michael (25 July 2016). "Encryption breakthrough: Scientists derive truly random numbers using two-source extractors". Tech Republic. Retrieved 12 June 2021.
  3. ^ Lynch, Peter (4 December 2018). "Random numbers plucked from the atmosphere". The Irish Times. Retrieved 12 June 2021.
  4. ^ McNichol, Tom (11 August 2003). "Totally Random". Wired. Conde Nast Publications. p. 2. Retrieved 23 October 2009. Mads Haahr, a lecturer in computer science at Trinity College in Dublin, designed the system
  5. ^ Klarreich, Erica (4 December 2004). "Take a chance: scientists put randomness to work". Science News. Archived from the original on 23 October 2009. Haahr's Web site [...] can generate up to 3,000 random numbers per second.
  6. ^ Johnson, George (12 June 2001). "Connoisseurs of Chaos Offer A Valuable Product: Randomness". New York Times. Retrieved 23 October 2009. Random.org generates unpredictable sequences of data using a radio tuned between stations, harvesting the atmospheric noise
  7. ^ Bialik, Carl (14 October 2009). "How Random Is the iPod's Shuffle?". Wall Street Journal. Retrieved 23 October 2009.
  8. ^ random.org: FAQ
  9. ^ random.org: History
  10. ^ "Your Quota". Random.org. Retrieved 10 April 2021.

External links