Testing and Certification of Online Slots

Have you ever thought about the process of testing online slot machines before they are released? Well, the following article will help you understand the mere process of testing and certification of online pokies as well as introduce regulatory bodies (testing companies) that stand behind these processes.

Slot Machines

In order to better understand the process of slots testing, one should first understand the basic principles behind the functioning of online machines.

The basic functioning component of every pokie is the Random Number Generator (RNG). Its main task is to create totally random sequences as fast as possible and, when it comes to online pokies, we’re talking about milliseconds.

It’s crucial to understand that online slots and RNG don’t possess a memory. RNG, in fact, represents a complex software consisted of mathematical algorithms that can create a random combination in an instant. As the reels turn, the RNG starts spinning random whole numbers, throwing them out one by one until there are as many numbers as there are positions on the reels. Each and every number ejected by the RNG represents a certain symbol in the game. The combination of displayed symbols depends on the combination of numbers provided by the Random Number Generator.


Each and every slot machine has to fulfill certain standards and regulatory conditions before it can be released to the global online gambling market. The process of testing should be done by independent specialized companies and laboratories. And not just that, every pokie needs to be separately tested for different regulators, such are the UK Gambling Commission, Malta Gaming Authority, Gibraltar, etc.

The following text contains data from several test reports. Since these data are strictly confidential, the name of the testing agency will not be mentioned, neither the title of the online slot machines that were tested.

The vast majority of inspected test reports contained data about the testing of two files: a configuration file containing an extension .xml (game settings) and RNG file containing the extension .jar. The file itself is determined by its name, version number and MD5 Hash Sum, which ensures that the files used during testing are exactly the same as the original ones that are built into a slot machine.

One of the reports showed that tests, both mathematical and statistical, are being executed on one million rows of sample game data, in order to confirm that RNG works in a totally random, fair way. The process of testing contains three groups of tests:

  • Probability tests for the number of incidences expected;
  • Randomness tests to ensure that the random incidence can’t be predicted in any way possible;
  • Uniformity tests to define that each and every outcome has an equal long-term chance of occurrence.

In this particular report and thanks to these tests, the theoretical return to player percentage of the tested online slot machine was decreased from 97.1%, as stated by the developer, to 96.7%, as showed in the test results.

All these tests are being used to ensure that the game fulfills the following conditions: the output of the game must be generated randomly and it must be absolutely unforeseeable.

This testing was performed by using the following test suites: χ2 tests, Wald-Wolfowitz tests, runs tests, frequency tests, and central limit theorem tests.

Requirements & Standards

The list below displays some of the operating and technical rules and standards that were tested and to which each slot machine must subject:

  • Games should function in a fairly manner, according to the general rules and the prevalent return to player percentage;
  • Feigningly displayed near-miss results are strictly banned;
  • The pre-determined maximum payout should be possible to obtain from one single game (features and bonuses included);
  • The speed of the game should be set in a way that allows the player to clearly see the outcome of each spin. The player is allowed to increase the speed of the game to the point where they can still distinctly notice the outcome of the spin;
  • Slots are not allowed to be adjustable in any way, each and every outcome carries the same chance of occurrence every time one plays the game (excluding the exceptions stated in the game rules);
  • The function of all embedded buttons should be distinctly indicated and all buttons labeled;
  • If the player selects the game, that doesn’t mean that the game should run immediately, forcing him to play it;
  • The output provided by RNG should fulfill the following requirements:
  • It should be totally independent in terms of statistics;
  • It should be distributed completely uniformly;
  • It should pass the tests for the absence of any kinds of patterns, as well as tests that authenticate the first two requirements;
  • It should be completely unforeseeable without the data such are seed value, algorithm and the implementation of the algorithm.

Testing Agencies

One can come across a solid number of independent testing companies. The list below shows the ones with the most credential so far:

The eCOGRA testing company was established back in 2003, headquarters in London, and since then it has tested thousands of the most popular games. It is specialized in certification and testing of online games and their software. Nowadays it provides services to over 80 leading online casinos.

GLI was founded back in 1989 in the USA. At first, it provided services to land-based casinos. Their international Europe lab was founded in the Netherlands back in 1998. The UK Gambling Commission has issued them a license to test all sorts of gaming accessories.

TST was established back in 1993, but since 2010 it operates under the management of the GLI, but they have retained the company’s name.

iTech is predominantly focused on testing of online gaming software. They have also obtained the license from the UK Gambling Commission back in 2014.


As seen above, all games and online gambling software solutions are being thoroughly tested and then certified. So, if you are having doubts about playing at a certain casino, just search after the approval seal, which means that the casino operates in a fair and safe manner.

We use cookies as set out in our privacy policy. By clicking on this pop up, you agree to our policies.