Online Slots Casino: Compare the best online slots casinos in the UK 2024

Peter Wilson

Online slots are some of the most popular casino games in the United Kingdom. Many online casinos in the UK will have thousands of online slot games from which to choose.

In this guide, we’ll show you how to choose top slot sites and the best online slots. We’ll also give you top tips to win real money on slots. So, let’s spin the reels and see what comes up…

Best casinos with online slots in the UK 2024

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Key takeaways

How we Rate the Best Online Slots Casinos

When writing our online casino reviews, we have a strict list of criteria. This enables us to look for the good, the bad and the ugly in each site. It also allows us to compare and contrast the key features of each of the online casinos. So, here’s our list of the best casino features:

✅ Welcome Bonus Offers

UK online slots players often begin their search for a new casino by looking at the welcome bonus. And the good news is that most welcome bonuses are great for UK players wanting to play slots online. Here, then, we're looking for multi-part bonuses with a healthy dose of free spins for some of the most popular slots – and low wagering requirements too (see below).

✅ Free Spins and Bonus Spins

Free spins for some of the industry's best slots will be included in the welcome bonus. We're talking video slots in the main. Jackpot slots clearly won't be included in free spins bonuses (imagine someone winning millions of pounds for free!). But we always look for regular free spins promotions on a weekly basis too. This is especially useful when trying out new slots.

✅ Wagering Requirements

New customers can struggle to wrap their heads around wagering requirements. Therefore, we expect online casino deals to be written in plain English. Also, we want to see standard wagering requirements of around 35 times the bonus amount – when it's also applied to the deposit, we suggest walking away. The same goes for when the wagering is in excess of 35x.

✅ Online Slots Selection

New customers looking to play slots online want a stellar game selection from which to choose. This should include classic slot machines, video slots and jackpot slots. And these should come from some of the best developers on the planet. Therefore, we always want to find not only a large selection of online slots but also that the top quality providers are on board.

✅ Other Casino Games

Having hundreds or even thousands of top online slot games is all well and good. But many UK players also want to mix things up from time to time. Therefore, other casino games should be plentiful. We're talking online roulette, blackjack and baccarat for starters. And a casino site will always get bonus points for serving up live casino games, poker, bingo and sports betting.

✅ Payment Methods

While casino bonuses and popular games take all the headlines, ensuring that your preferred payment method is supported is vital for a good experience. We check things like whether or not a payment method is accepted for welcome bonuses, if any fees are charged and if the withdrawal times are within industry standards. All these things can impact your game time.

✅ Customer Support

Shit happens. And when something goes wrong in the middle of the night, you'll want to resolve that issue as soon as possible. Having a knowledgeable, friendly and prompt customer support team on your side is key. That's why we routinely test response times and answers. And there are bonus points for 24/7 support via live chat, email and a UK freephone number.

✅ Safety and Security

We won't touch unreliable and blacklisted sites with a barge pole. And you shouldn't either. That's why we always look for full encryption across all pages of an online casino. Without these basic protocols, you could be risking your personal or financial data. On the same note, we will praise any site that offers two-factor authentication to help protect customer info.

✅ Casino Licensing

A site targeting UK players without a casino license from the esteemed UK Gambling Commission is a huge red flag. The UK Gambling Commission works tirelessly to protect online casino players from rogue actors. That's why we go looking for a valid UKGC license before even considering a site for inclusion in our expert online casino reviews section.

GamblingAuthority’s All-time Top 5 Online Slots

Now that we know about slot genres and how they work, let’s explore the most popular slots. This is by no means an exhaustive list – UK players are spoilt for choice when it comes to online slots. But these are perennially popular and happen to be GamblingAuthority faves too:

Starburst Slot by NetEnt

NetEnt’s five-reel, three-row Starburst is an insanely popular online slot game. There are many factors for why this may be – not least because it frequently shows up in online casino welcome bonuses with free spins. It’s easy to play, has a decent RTP of 96.09% and has low volatility – meaning frequent payouts for players. The 10 paylines pay both ways. And the expanding wilds and respins turn this bejewelled space adventure into a stellar experience.

Gonzo’s Quest Slot by NetEnt

Gonzo’s Quest is another blockbuster from NetEnt. And “blockbuster” is right on the money as the stone block reels regularly explode to create new winning opportunities. Set in an ancient Incan city, the 20-payline game features avalanche reels, multipliers and Free Fall rounds where your free spins can really pile up. And all along, Gonzo himself watches the action and reacts whenever you grab a win. In short, this is a beautiful slot game with an RTP of 95.97%.

Book of Dead Slot by Play’n GO

Another one that is often included in welcome bonuses with free spins, Book of Dead takes us back to Ancient Egypt. You play as the famous archaeologist and treasure hunter Rich Wilde (think Indiana Jones) as you hunt down Scatter Symbols, Expanding Symbols and Special Expanding Symbols. Doing so essentially unlocks a chain reaction of free spins that can get really insane. Plus, with an RTP of 96.21%, you can be sure of multiple wins along the way.

Big Bass Bonanza Slot by Pragmatic Play

Rather than low-frequency music, this one is instead all about fishing for bigger and bigger wins. The slot game from Pragmatic Play features five reels, 10 paylines and a rather healthy RTP of 96.71%. Plus, in addition to the chance to win free spins, there are wild retriggers and multipliers. Furthermore, due to its popularity among casino players, there’s also a sequel called Bigger Bass Bonanza and a special Big Bass Bonanza Megaways version out not too.

Mega Moolah Jackpot Slot by Microgaming

The jackpot slot to end all jackpot slots. Most of the biggest online casino wins in the last decade have come from players hitting the big one on the Mega Moolah series. That’s right, there’s more than one. To name but a few, there’s the original Mega Moolah, as well as Mega Moolah Isis, Absolootely Mad, Atlantean Treasures, Juicy Joker and Mega Vault Millionaire. So, if you want the chance to win millions of pounds on a single spin, be sure to try them out.

See our top 5 list of the best online slots ever made!

Honourable Mentions 👍

There are thousands of top slots out there. Too many to cover here. Therefore, we wanted to give a special shoutout to the following: Divine Fortune, Rainbow Riches, Fishin Frenzy, Jack and the Beanstalk, Immortal Romance, Thunderstruck II, Legacy of Egypt and Wild Toro 2.

Types of Online Slot Games in the UK 🎰

While each slot game is different and new slot games continue to push the format, there are some broad categories into which most fall. These definitions affect the complexity and types of bonus rounds of online casino slots. Below, we’ve rounded up the five main slot categories:

Classic Slots and Fruit machines

Classic slots (commonly known as fruit machines in the UK) are based on the one-arm bandits of yesteryear. They have a retro feel and symbols comprised of traditional fruits, BARs and bells. They are dead simple too – often only featuring a single payline in the middle and little to no bonus rounds. Because of this, they offer an easy route for beginners to play online slots.

Online Video Slots

The most common form of slot is the video slot. They can be simple or vastly complex. Some feature thousands of paylines (such as the Megaways slots), while others throw in different bonus rounds that are mini-games in and of themselves. The game mechanics are just as weird and wonderful, too, with things like cascading reels and huge multipliers adding excitement.

Branded Video Slots

Similar to video slots, branded slot machines go one step further. They are tied to huge media franchises. For example, TV shows like The Walking Dead and Rick and Morty, movies like The Lord of the Rings and Gladiator and famous artists like Guns N' Roses and Jimi Hendrix. And because branded slots have much more money behind them, the quality is extremely high.

Progressive Jackpot Slots

Progressive jackpots are what you read about whenever there's a big win. That's because a small amount of each wager is added to a prize pool over weeks or months from linked video slots all over the world in thousands of online casinos. In turn, this means some progressive jackpot slots like Mega Moolah and Mega Fortune offer millions of pounds in prizes on a single spin.

Crypto Slots

Lastly, there's a new breed of online slots based on the same blockchain technology that powers Bitcoin casinos. You may, in fact, see these games given the name Provably Fair. That's because blockchain technology is basically a write-only digital ledger or spreadsheet showing every transaction. In this, way every single spin on a crypto slot can be tracked and traced.

Online Slots Explained – How do they work? 🤔

Playing online slots is fairly self-explanatory. You choose your overall bet level and the number of paylines (if available), then hit spin. The reels turn and land on a certain combination. If you get (usually) three or more matching symbols on an active payline, you win! And all these things can be looked up in the paytable. But what’s going on behind the scenes? Let’s find out…

Random Number Generator (RNG)

All online slots use a random number generator (RNG) algorithm to generate the results seen on the reels. The algorithm generates thousands if not millions of random numbers per second. As soon as a player hits spin, a random number is selected and used to calculate the results according to a formula. In this way, each spin is random and weighted according to the RTP…

Return to Player (RTP)

Return to player (RTP) is expressed as a percentage. So, while table games use house edge to calculate the probability of winning, slot machine RTPs tell a player the average expected payout. So, if an RTP is 97%, a player can expect an average return of 97p for every £1 wagered – with the casino making a 3p profit. However, it’s possible to win or lose more than the average.

Volatility and Variance

Last up, we have volatility or variance. This is usually expressed as high, medium or low. And it tells us the expected distribution of wins and their size. So, high volatility means a player will win less often but will win big when it does happen. Low volatility means a player will win frequently but the amounts will be on the small side. Medium is halfway in between the two.

Best Slots Bonuses for UK players 💰

We’ve covered all the different types of slot games including jackpot slots, but what about casino bonuses? These give you the chance to play slots online with free spins and bonus cash from the casino. With or without a casino bonus code, here are the promos you can expect for slots:

Welcome Bonus

The best casino welcome bonuses for playing online slots combine a multi-part cash bonus and free spins. In this way, you can play your free spins on whatever selected game(s) has been chosen by the online casino. Then, you can use the casino bonus on any of the eligible slot games.

Free Spins Bonus

As well as picking up a bunch of free spins as part of your welcome bonus, you should be given another batch each week or at least when new slot games are released. We always check the casino promotions page to see what’s what each week – note that you might need a bonus code.

No Deposit Bonus

New customers in the UK can often get a casino bonus without making a first deposit. Quite often a no deposit bonus will consist of some low-value free spins enabling you to play online slots without risking your own cash. You’ll still need to complete the wagering requirements but it’s still a great deal.

Cashback Bonus

High rollers tend to prefer cashback bonuses over free spins because they can get more for their money. So, if a slot games session doesn’t go according to plan, they can opt to receive a percentage of their losses back. This exclusive bonus usually operates on a weekly basis, too.

Slots Tournaments

Not so much a casino bonus, but more of a promotion to see if you can top the leaderboard and claim all the bragging rights. These time-limited slots tournaments can sure be exciting and often force you to try new online slots that you hadn’t considered playing before. Recommended!

Discover the best casino slots bonuses for UK players

Top 10 Leading Developers of Online Slots UK

All online slots (except a few rare exceptions made by online casinos) are developed by games providers. And if you tend to like a slot game produced by one company, you’ll probably dig their other online slots. Here, then, we want to give an overview of the top 10 slot providers:

⭐ NetEnt

Swedish games provider NetEnt (formerly Net Entertainment) is one of the biggest and the best in the gambling industry. After two decades, the company has been bought out by Evolution Gaming but still operates more than 200 high-quality slot games. Its biggest hits include Starburst, Mega Fortune, Blood Suckers, Gonzo's Quest, Divine Fortune and Narcos.

⭐ Microgaming

Microgaming helped kickstart the online casino slots industry from the Isle of Man back in 1994. It has since gone on to produce some of the best progressive jackpot slot games and video slots. Plus its titles show up in thousands of UK online casinos. Here's a taster of that prolific output: Mega Moolah, Book of Oz, Jurassic World, Thunderstruck II and Bonanza Megaways.

⭐ Playtech

Founded in Estonia in 1999 and now headquartered in the Isle of Man, Playtech is one of the largest games providers on the planet. In fact, the company goes far beyond slot machines and into poker, bingo and sports betting too. As for a few recommendations on the slots front, try out Age of the Gods, Gladiator: Road to Rome and Frankie Dettori's Magic Seven for starters.


Based in Reno, Nevada, International Game Technology (more commonly known as IGT) got its start making physical slot machines for casinos around the world. With the popularity of online slots taking over from slot machines, IGT ported their best slots over to online casinos. Top IGT slots include Cleopatra, Da Vinci Diamonds, Pixies of the Forest, Wolf Run and more.

⭐ Pragmatic Play

Based in Gibraltar, Pragmatic Play works with many of the best online casinos, providing online slot games in a variety of genres. The company has won numerous gambling industry awards for its innovative features and top-quality video slot and jackpot slot games. Be sure to check out Wild Wild Riches, The Dog House, Fruit Party 2, Chicken Drop and Lucky, Grace & Charm.

⭐ Novomatic

Austrian slot game manufacturer started back in 1980. So, it has plenty of experience building slot game cabinets. Taking that knowledge and huge games portfolio into the online casino world was a natural move, especially after a series of high-profile mergers and acquisitions. Here's a taste of its slot menu: Book of Ra, Pharoah's Tomb, Sizzling Hot and Lord of the Ocean.

⭐ Betsoft

Founded in 2006, this Malta-based games provider has gone on to produce more than 200 high-quality slot games and jackpot slots. One thing you can be certain of with Betsoft slots is the brilliant graphics, making them a joy to play. And if we had to choose which slots to showcase, we'd go with SugarPop, Back to Venus, Primal Hunt, Tower of Fortuna and A Night in Paris.

⭐ Play'n GO

Plucky Swedish games provider Play'n GO has offices in various gambling hotspots around the world, including Malta and Gibraltar. Utilising a startup mentality, the slot game provider has quite a few tricks up its sleeve for producing engaging and unique casino games. Be sure to sample the likes of Book of Dead, Reactoonz, Moon Princess, Honey Rush and Golden Colts.

⭐ Big Time Gaming

Launched in 2011 in New South Wales, Australia, Big Time Gaming (or BTG for short) is synonymous with innovative slot game mechanics. For example, the team created the Megaways concept, which is now licensed by other slot providers. BTG produces top slots of its own too: Bonanza Megaways, White Rabbit, Lil' Devil, Extra Chilli and Who Wants to be a Millionaire.

⭐ Yggdrasil

Last but not least, we wanted to highlight the gorgeous online slot games of Malta-based Yggdrasil. The superbly crafted titles in the Yggdrasil portfolio will make you want to continue playing into the wee hours (as we often do ourselves). To get started, check out the likes of Jungle Books, Double Dragons, Orient Express, Vikings Go Wild and Holmes & the Stolen Stones.

Find out if online slots are better than traditional casino slot machines

Playing Online Slots vs. Land-based Casino Slot machines

Now that we understand the mechanics of slot machines, it’s time to compare online slots with their real-world counterparts. Well, essentially, the two function in the same way. However, because a traditional land-based casino has considerable overheads such as rent, electricity and staff salaries, the RTP of land-based slot machines is very low (around 80%).

For those playing online slots, the advantages are clear. Because there are fewer overheads for an online casino (and the games can be replicated ad infinitum all around the world), the RTPs of online slots are very high indeed. In fact, you’ll find many video slots boasting RTPs of around 95%. And it’s perfectly possible to find online slot games with a massive RTP of 98%!

Alternative Online Casino Games

Sometimes you might not be in the mood for Rainbow Riches or jackpot games. Instead, you might want to break things up with a different form of online gambling. And best of all, loads of online casinos specialising in video slots will also have one or more of the following casino games:

Table Games 🎲

The foundations of online casinos begin with traditional table games. We are, of course, talking about online roulette, online blackjack and online baccarat. On top of that, you can often find sic bo, craps, mahjong, pai gow poker and many more, some with a live dealer…

Live Casino Games 🤵

If there’s one category that has taken online casinos into the 21st Century it would be live dealer games. Now, you won’t find any live casino slots, for obvious reasons, but all the classic table games will be present. Plus, there are some brand-new genres based on TV game shows.

Poker 🃏

While the majority of video slots and jackpot games are entirely based on luck, poker is very much based on skill (and a little bit of luck). You’ll find Texas Hold’em, Omaha, Seven Card Stud, Five Card Draw and many more. So, if a slot takes it out of you, try on your poker face.

Bingo 🖍️

Massively popular with the older generations in the United Kingdom, bingo has reinvented itself at online casinos. No longer a game to be played in boring halls, online bingo can be fast and exciting. Also, fans of slot machines should check out Slingo, which combines slots and bingo.

Sports betting ⚽

Last but not least, you might want to take a break from pursuing that progressive jackpot by betting on football, cricket or horse racing. Plus, you can make your bets, watch the big game and play slot games when the adverts come on. In this way, you get the best of both worlds.

Best UK Online Slots Sites for Mobile Players📱

Most UK online casinos are compatible with mobile devices like the iPhone, iPad and their Android equivalents. To start playing on your phone or tablet, simply point your mobile browser at your desired casino site. Each one will be fully optimised for smaller touchscreen devices with all the same features and slots available. Or you can download a slots app…

Android and iOS Slots Apps for Mobile

While we much prefer to use the mobile versions of online casinos, some players prefer a dedicated app. The only advice we would give here is to use the slots apps provided by UK online casinos. There are plenty of other apps out there but the quality control is not usually very high – and more often than not, you cannot win real money playing slots via a free app.


We hope we’ve made your time in the casino lobby easier. There are so many brilliant online slots out there that it can sometimes be difficult to decide. We hope we’ve also helped you pick one of the many cash bonuses and free spins promotions out there. Now you should be ready to start playing casino slots online. Just remember to play safe and play responsibly.

Online Slots FAQ

What are the best progressive jackpot slots?

By far the biggest online slots in terms of potential jackpots are Mega Moolah, Mega Fortune Dreams, Arabian Nights, Hall of Gods and Divine Fortune. But it's all down to personal preference. For more information about games and promotions, see our Jackpot Slots article.

What is the best slots site for UK players?

There isn't a definitive number one UK slots site. Instead, it's all about weighing up the game selection with things like the first deposit bonus and free spins, available payment methods and level of customer support. See above for more about the finer details of online casinos.

What do RNG and RTP mean for online slots?

RNG stands for "random number generator", which is an algorithm used in slots to keep the result from being predictable. RTP means "return to player" and it gives an idea of the average payouts a player can expect. A 95% RTP means an average payout of 95p for every £1 wagered.

Which UK online casino has the best payouts?

It's not usually the online casinos that set the payout rates for online slots. Instead, it's the game providers that do this. So, it's worth searching for the highest RTP online slots to get the best payouts. For more information, refer to our dedicated article on the Best Payout Casinos.

Can I play online slot games for free in the UK?

Yes, but you will either need to have an online casino account or else prove that you are over the age of 18 to play demo slot games. That's because the UKGC wanted to clamp down on minors accessing slot games and other casino entertainment while at an impressionable age.

Are online slots rigged to make me lose money?

If you play at an online casino licensed by the UKGC, you won't have any problems because the slot games will have been independently tested for fairness. We can't say the same about offshore sites, however. That's why we only recommend playing at UKGC-licensed casinos.

What does volatility mean for online slots?

Essentially, volatility gives a player some basic information about the frequency and size of payouts. High volatility means that payouts are few and far between but are often sizable when they do happen. Low volatility means fairly frequent payouts that are low in value.

Does the UKGC license online slots in the UK?

The UKGC does not license individual slot games. However, it does license both online casinos and slot game providers that operate in the UK. For the testing of casino games, third-party organisations such as eCOGRA will independently verify the legitimacy and fairness of a game.

Peter Wilson
Peter Wilson
58 Articles
27 Reviews

Peter is our Editor-in-Chief at Gamblingauthority. He has more than eigth years of experience from the iGaming industry and is a valuable resource for everything related to online casinos.

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