How to tell if online casino is rigged: the short answer
You cannot prove a casino is fair by playing it, and you cannot prove it is rigged from a bad session either. What you can do is check the things a rigged operator would struggle to fake: a licence that matches a regulator's public register, evidence that games and random number generators were independently tested, readable terms, and a complaints route that ends outside the casino. This guide explains each, using the UK Gambling Commission's own pages as the benchmark.
Gambling is a regulated activity and this is consumer explainer journalism, not a recommendation of any site, and we do not link to or rank operators. We also did not test, audit or play at any casino for this piece. Everything attributed below comes from regulator pages we opened on the day of writing, and where we are explaining general principles rather than citing a rule, we say so.
Why a bad run of results is not proof
The first instinct of most players who lose is to suspect the game. That is understandable, but it is weak evidence. A slot or a roulette spin is designed to be random, and random sequences contain long streaks that feel patterned. A short run of losses, even a painful one, is exactly what a fair game produces regularly, because every spin is independent of the last one.
The better question is structural: is there an independent party whose job is to check the random number generator, and can you verify that party exists? That shifts the test from how you feel about your results to whether the machinery around the game can be audited. Honest operators can be audited. Operators that avoid being checked are the ones that deserve suspicion, and a missing licence is the clearest version of that.
“You cannot take your complaint to an ADR without first going through the gambling business's complaint process.”
Check 1: verify the licence against the public register
The Gambling Commission tells players to confirm that a business holds a Commission licence before gambling. It says licensed businesses must display that they are licensed and also provide a link to its public register. The register shows what type of activities a business can offer and whether the Commission has taken regulatory action against it.
The practical step is not to trust the badge in the footer but to click through to the register and compare. The Commission's guidance asks you to check that the licence details, including activities and website domain names, match what the register says, and to look for the business address, trading names and current licence status on the site. A footer logo that does not link anywhere, or a domain that is not on the register, is a reason to stop. The Commission says a licensed business means you are protected by consumer and gambling protection rules in Great Britain, which is the practical value of the check.
Be clear about the limits. The register covers businesses licensed in Great Britain. A site licensed elsewhere may be legitimate in its own market, but a British player gets Commission protection only from a Commission licence. If you live outside Great Britain, the same logic applies: find your own regulator's register, and treat a site that cannot point to one as unaccountable.
Check 2: understand what RNG testing actually covers
Random number generator, or RNG, testing is the main technical safeguard. Under the Commission's Testing Strategy, which was last updated on 13 September 2024, RNG testing has four areas. Testers review the RNG documentation to understand how it is implemented, research the algorithm or hardware for known weaknesses, check that the source code matches the documentation, and statistically test the raw RNG output and the scaled or shuffled data. Any non-compliance is reported to the supplier and re-evaluated once resolved.
The Commission states the gate plainly: all new games and RNGs can only be released once testing has been completed and the report provided to the Commission. Licensees agree the testing scope with a test house, and the Commission publishes a list of approved test houses. Licence categories that need RNG and games testing by an independent test house include remote casino, remote bingo, remote pool betting, certain virtual events betting and remote lottery licences with entries over £250,000 per year.
What this does not tell you is that every spin you take is individually audited. Testing certifies the generator and the game design before release, and the licence obliges the operator to keep to the standards. It is a strong control, but it is a pre-release and ongoing compliance system, not a live guarantee on your account, and nothing in the Commission's page says otherwise.
Check 3: read the terms before you deposit
The Commission also tells players to look at the terms and conditions for each gambling product, so you understand what you are playing. Treat that as a fairness check, not a formality. Unclear wagering conditions on promotions, restrictions you only discover after a win, or limits on withdrawals that appear late in the process are the typical ways a legitimate-looking site treats players badly without touching the games at all.
The Commission specifically flags restrictions on introductory promotions, such as a minimum spend before a reward is paid. If a promotion's conditions cannot be found, or change depending on who you ask, that is a signal about how disputes will go. Take screenshots of the terms that applied on the day you deposited, because you will need them if you complain.
Provably fair crypto casinos: what the label does and does not mean
Some crypto-focused sites advertise a provably fair system, where the player can check cryptographic data after each round to confirm the outcome was not changed. As a general principle that is a real technique, and it addresses one narrow question: was this round's result altered after you bet. We have not tested any such site and cite no specific rule, so treat this as an explanation of the idea, not an endorsement.
What provable fairness does not address is everything else on this list. It does not tell you whether the operator is licensed or accountable to a regulator, whether terms are fair, whether withdrawals are honoured, or what happens in a dispute. A self-published verification tool is also controlled by the operator unless an outside party checks it. The licence and independent testing in the UK system exist precisely so you are not relying on the operator marking its own homework.
What to do if you think a casino cheated you
Start with the business. The Commission's guidance says to complain directly to the gambling business first, check the terms attached to your account, give full details such as dates, times and amounts, share evidence and keep copies of everything. The free tool Resolver can help you submit a complaint, though the Commission notes it is an independent company and not every business accepts complaints through it.
The business has 8 weeks from receiving your complaint to resolve it, and it must tell you the result and next steps. If you are unhappy, you may be able to escalate to an Alternative Dispute Resolution provider, which is an independent service. The Commission is blunt about the order: you cannot take a complaint to ADR without first going through the business's own process.
The Commission also says its feedback form is not for complaints and it will not reply to them. For concerns about a gambling business, use its contact page. If you are struggling with your own gambling, the Commission lists helplines on its site, including 0808 8020 133 in England and Scotland and 0808 2819 265 in Wales.
Our take: the five checks in order
If you want one routine, run these in order before depositing: licence on the register and matching domain, evidence the operator discloses its testing, terms read and saved, a known complaints route, and a deposit you can afford to lose. None of these proves a game is fair, but together they make a rigged operator far easier to spot and far harder to complain about.
The honest summary is that fairness in regulated online gambling is enforced by accountability, not by trust. Where there is a licence you can verify, tested software and a route to a free independent dispute service, you are not relying on goodwill. Where those are missing, no amount of slick design or promotional language should reassure you, and a losing streak is not the evidence either way.
Frequently asked
How to tell if online casino is rigged?
You cannot tell from results alone, because random games produce long losing streaks. Instead check what a rigged operator struggles to fake. Confirm the licence by clicking through to the regulator's public register and matching the domain and activities. Look for evidence the operator's games and random number generators were independently tested. Read the terms before depositing, and know the complaints route. A site that fails the licence check is the biggest warning sign, and a regulator's register is the authority, not a footer badge.
How do I check an online casino licence in the UK?
Look for the licensed-business statement on the site, then use the Gambling Commission's public register to confirm it. The Commission says licensed businesses must display that they are licensed and link to the register, which shows the activities they can offer and any regulatory action. Check that the licence details, including activities and website domain names, match the register. The register covers businesses licensed in Great Britain, so a site licensed elsewhere is outside this protection.
What is RNG testing in online casinos?
RNG testing checks that a random number generator behaves fairly. Under the Gambling Commission's Testing Strategy it has four areas: reviewing the documentation, researching known weaknesses in the algorithm or hardware, checking the source code matches the documentation, and statistically testing raw and scaled output. New games and RNGs can only be released once testing is complete and the report is provided to the Commission, which publishes a list of approved test houses.
Can I complain if I think an online casino cheated me?
Yes. Complain to the gambling business first, with dates, times, amounts and evidence, and keep copies. In Great Britain the business has 8 weeks to resolve it and must explain the outcome and next steps. If you are still unhappy you may escalate to a free, independent Alternative Dispute Resolution provider, but only after the business's own process. The Commission says its feedback form is not for complaints and it will not reply to them.
Does a losing streak mean an online casino is rigged?
No. Each spin or hand in a fair game is independent, and random sequences naturally include long streaks that feel patterned. A losing run is weak evidence on its own, because a fair game produces them regularly. Better evidence is structural: a missing or mismatched licence, no sign of independent testing, terms that block withdrawals, or an operator that refuses to follow a complaints process. Those are checkable, which is why this guide focuses on them rather than on your results.
Are provably fair crypto casinos safer?
Provable fairness is a technique that lets a player verify after a round that the outcome was not altered, and it addresses only that narrow question. It does not tell you whether the operator is licensed, whether terms are fair, whether withdrawals are honoured or what happens in a dispute. We did not test any such site. A licence you can verify and independent testing still matter, because a self-published tool is controlled by the operator unless an outside party checks it.