Last updated: 18 July 2026
Behind the RNG
Every licensed online slot and virtual table game needs a way to produce outcomes that players cannot predict or influence. That mechanism is a random number generator — RNG — running on the operator’s or supplier’s servers. The phone in your hand is just a display client; tapping spin does not “aim” the result.
What an RNG does
Software RNGs continuously generate numbers. When you press spin or deal, the game maps the current number (or a short sequence) to a reel stop, card or roulette pocket according to the game’s published rules. Changing device, network or orientation does not rewrite that mapping on a UKGC-licensed title.
Why independent labs exist
Operators and game studios submit RNG implementations and game maths to accredited testing houses. Labs such as eCOGRA, GLI (Gaming Laboratories International), iTech Labs and BMM Testlabs are among those commonly referenced in the industry. They evaluate statistical randomness, implementation integrity and whether the game behaves as its specification claims.
A seal or certificate number on a help page means a specific build was tested against a standard — not that every future session is manually watched. Certificates expire or need renewal when software changes; responsible suppliers re-test after material updates.
UK Gambling Commission expectations
Remote licensees must ensure games are fair and that RNG systems are suitably tested. The Commission’s technical standards set out what fairness and testing look like for the Great Britain market. Player-facing sites must also make return-to-player (RTP) information available where required — RTP is a long-run statistical average, not a promise for your evening session.
What seals are not
A lab logo is not a tip on which game will pay next. It does not override house edge. It does not replace safer-gambling tools. Treat seals as evidence of process, then set your own limits.
Live dealer games
Live roulette and blackjack use physical equipment under camera, with studio procedures and often secondary systems for card shuffling and wheel integrity. Those products follow a different assurance path than pure RNG slots, but they still sit under the operator’s UK licence when offered to GB players. Etiquette for those tables is covered on our live dealer etiquette page.
Checking on mobile
Open a game’s information panel (often an “i” icon) on the brands we review — LeoVegas, Spin Genie, Duelz and others — and look for supplier name, RTP summary and links to fairness information. If nothing is documented, prefer titles that publish it clearly.