How to Verify Fairness: RNG, Audits, and Certification

Fast: Check a casino license on the regulator’s official website, click on the logo of a testing laboratory and check the certificate on the laboratory’s official website, read the RTP and the date of the last check of the game, and for the bitcoin casino check a couple of “provably fair” with seed and hash. Don’t play on sites with a false or expired seal and a non-existent license number.

Why Fairness Matters in Online Gambling

This is the most important part: you should only gamble on fair websites. Fair doesn’t mean that you always win. It means that the games use true randomness, the math has been verified by third-party labs, and that the operator must adhere to a certain standard of conduct, licensed by a regulatory body. All of this prevents behind-the-scenes manipulation and keeps you from being gamed.\nIn this article, you’ll learn how to verify fairness. I’ll teach you about random number generators, audits, and certificates. I’ll even show you how to check “provably fair” games on Bitcoin sites. At the end of this, you should be able to verify a website, a game, and a certificate within 10 minutes.

In this guide, you will learn simple steps to check fairness. We will explain RNGs (random number generators), audits, and certificates. We will also show how to verify “provably fair” games on crypto sites. By the end, you will know how to confirm a casino, a game, and a seal in about 10 minutes.

What “Fairness” Means: Randomness, RTP, and Volatility

Return to Player (RTP): This is the payback percentage over a period of time. An RTP of 96% means you win $0.96 over the long term for every $1 bet. That doesn’t mean you can’t have short-term losses. The RTP is based on the long term.

Volatility: This is an indicator of the bumpiness of the ride. High volatility means bigger wins less frequently, with bigger dry periods between. Low volatility means smaller wins more frequently, with less time between them. Streaks are possible in either case. Streaks don’t imply rigging.

Myth to get rid of: “These games are tighter at night.”

No laboratory or regulator is in the business of allowing time-keeping sleights-of-hand.

How RNGs Work (and Why Certification Matters)

Most online games use a pseudorandom generator. It starts with a secret seed and makes a long stream of numbers. Good RNGs pass many hard tests. Some systems also use hardware RNGs or crypto hashes to add more entropy (more surprise in the numbers).

The typical practice for most online games is to utilize a pseudo random number generator. They have an unknown seed, and generate a sequence of numbers. A good PRNG will pass a lot of rigorous testing. Some systems also use hardware RNGs or crypto hashes to add more entropy (more surprise in the numbers).

Stats tests: The numbers pass known batteries of tests for randomness.
Code review: The lab reviews the build, settings, and how the game uses the RNG.
Change control: Any update to the game needs new checks before it goes live.

There are three major areas labs test:

Learn more about RNG best practice at NIST SP 800-90.

The Role of Independent Testing Labs

You can learn more about RNG best practice here: NIST SP 800-90.

Major labs you will see:

eCOGRA (well-known for fairness and compliance)
GLI — Gaming Labs International (GLI-11, GLI-19 standards)
BMM Testlabs
iTech Labs

Some of the labs you will commonly encounter include:

Click the seal on the casino page. It should open a page on the lab’s domain (for example, ecogra.org, gaminglabs.com).
On the lab page, look for the casino name, certificate ID, scope (what is covered), and dates.
Make sure the URL is HTTPS and the domain matches the lab. A static image is not proof.

Licensing and Regulatory Oversight

A strong license means rules, audits, and ways to file complaints. Top regulators include:

UK Gambling Commission (UKGC)
Malta Gaming Authority (MGA)
AGCO and iGaming Ontario (Canada, Ontario)
New Jersey Division of Gaming Enforcement (DGE)

Other jurisdictions exist, like Curaçao eGaming and Kahnawake. Many sites there are fine, but oversight is often lighter. Do extra checks on seals, game providers, and complaint history if you use them.

Then there are other licensing bodies such as Curaçao eGaming and Kahnawake. There are some great sites licensed there, but the regulation may not be as strict. If you play at such sites, make sure to dig a little deeper into their trustworthiness by looking at their certificates, checking which games and software they are offering, or looking up any past scandals.

Find the license number in the casino footer or “About/Terms.”
Search that number on the regulator’s own site (for example, the UKGC public register).
Check status, brand names covered, and any warnings or actions.

Audits and Certifications to Look For

Trust signs that matter:

Game-level certifications: The game title and build (version) were checked.
RNG certifications: The engine was tested with strict standards.
Payout reports: Some operators publish monthly or quarterly reports.
Info security: Look for ISO/IEC 27001 for the operator’s data security.

Common standards:

GLI-11 (gaming devices) and GLI-19 (interactive gaming)
eCOGRA eGAP requirements (fairness, player protection, responsible gambling)

Version control matters: A “certified” badge is not forever. If a game updates, it can need retesting. On the lab page, look for dates and version numbers. If the site shows a seal but the lab page is out of date, ask support or avoid the site.

Provably Fair for Crypto Casinos (Step-by-Step)

“Provably fair” lets you check each round yourself. It uses a server seed (hidden at first), a client seed (you can set it), and a nonce (a counter). The site shows a hash of the server seed before you play. After you play, it reveals the seed. You can hash it and see that the hash matches. Then you can recreate the result with the seeds and the game’s formula.

"Provably fair" allows you to verify each round for yourself. It works by using 3 things: A server seed (not disclosed to you), a client seed (generated by you), and a nonce (counting variable). They display a hash of the server seed before you play, and then display the seed after you play. You can hash it to verify that it matches, and then you can calculate the result yourself with the seeds and the game's algorithm.

Before play, copy the server seed hash shown by the site.
Set your own client seed if the site allows it.
Play a few rounds. Note the nonce for each round.
After the site reveals the server seed, hash it (for example, with SHA-256) and confirm it matches the old hash.
Use the server seed + client seed + nonce in the site’s open formula or tool to recreate the outcome. The result should match what you saw.

Red flags:

No way to set a client seed.
No public tool or formula to verify outcomes.
Server seed changes too often without proof, or the hash does not match.

Learn more about hashing in the NIST docs: NIST Hash Functions.

Player Checklist: Verify a Casino’s Fairness in 10 Minutes

License: Find the license number and check it on the regulator’s site (UKGC, MGA, AGCO/iGO, NJ DGE).
Lab seal: Click it. Confirm the certificate on eCOGRA, GLI, BMM, or iTech Labs domains.
RTP: Open a game. Look for RTP info in the help screen. If not shown, check the game provider’s site.
Dates: On the lab page, check the issue date and scope. Avoid stale or mismatched entries.
Build version: Make sure the version on the lab page matches the game or release notes.
Crypto check: If “provably fair,” verify a few rounds with the seed/hash steps.
Providers: Search for known studios (for example, Play’n GO, NetEnt, Evolution). Reputable studios work with top labs and regulators.
Terms: Read bonus and withdrawal rules. Watch for vague or harsh clauses (for example, “we can void wins for any reason”).
Complaints: Look up player complaints on trusted forums or review hubs. See how the casino responds and resolves issues.
Safety tools: Check for deposit limits, time-outs, and self-exclusion. Good sites make these easy to use.

Red Flags and Common Pitfalls

Fake seals: Seals that do not click, or links that do not go to a lab’s domain.
Dead links: The seal opens a 404 page, or the casino name does not match the certificate.
No license number: Only says “operating under master license” with no way to verify.
Unclear RTP: No RTP info in-game, or a very low variant with no clear notice.
Harsh terms: Rules that let the site seize wins for tiny mistakes.
Too-good bonuses: Huge offers with tiny time windows or bet rules that block real play.

Where to Find Vetted, Audited Casinos

Curated lists can save time. A good list will show the license number, link to the regulator page, link to the lab certificate, list RTPs, and note the last audit date. It should also track complaints and how the casino fixed them, if at all.

A good list can cut that down though. What to look for in a list is a license number, a link to license page, a link to lab certificate, RTP listed, date of last audit, complaint history, and whether they were resolved by the casino or not.

FAQs

Are online casinos rigged?

Licensed casinos must use tested RNGs and audited game math. The house has an edge, but randomness and RTP get checked by accredited labs and regulators.

How often are games retested?

The house will always have an advantage, but the randomness and RTPs are regularly checked by independent labs and the regulators themselves.

Can casinos change RTP after launch?

When we launch something new or make a significant update.

Are live dealer games audited?

Check the lab page for dates and versions.

Are Curaçao casinos fair?

There may be multiple RTP versions depending on the jurisdiction.

Is “provably fair” tamper-proof?

RTP can usually be found within the game itself or on the provider’s website.

Glossary

RNG: Random number generator used to pick game results.
RTP: Long-term payback percent of a game.
Volatility: How often and how big wins tend to be.
Provably Fair: A method to verify each game round with seeds and hashes.
Seed/Nonce: Secret value and counter used to make random outputs.
GLI: Gaming Labs International, a major testing lab.
eCOGRA: A well-known testing and standards body.
ISO/IEC 17025: Standard for lab testing quality.
Certification vs. License: A lab tests a game (certification). A regulator allows a site to operate (license).

Final Thoughts and Responsible Gambling

The majority are OK, but more relaxed. Extra verification: license, lab stamps, business associates, complaint record.

Gamble only with money you can afford to lose. Set limits. Take breaks. If you need help or advice, use these resources:

BeGambleAware
GamCare
National Council on Problem Gambling (US)

Sources and Further Reading

eCOGRA
Gaming Labs International (GLI) Standards
BMM Testlabs
iTech Labs
UK Gambling Commission and the Public Register
Malta Gaming Authority
AGCO and iGaming Ontario
New Jersey DGE
NIST SP 800-90 (RNG)
ISO/IEC 17025
ISO/IEC 27001
NIST Hash Functions