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The Best Online Slots Reviewed in 2021

Browse thousands of the best online slots and quickly access information on RTP, volatility, free spins, jackpots, and more. Read honest and transparent slot reviews of the industry’s leading casino providers, such as Play’n GO, Big Time Gaming, and Pragmatic Play.

Whether you want to play real money slots or try out new games, we’ve got you covered. Find the best online slots by provider and feature, learn about the different kinds of volatility and how they might affect your chance of winnings.

For those of you that cannot wait, here are five top slots for 2021, which players across the world have rated highly:

  • Big Bass Bonanza
  • Goblin’s Cave
  • Mega Moolah
  • Wolf Gold
  • 9 Pots of Gold

We also recommend checking out our guide on RTP (Return to Player), a crucial factor in choosing online slot games.

Introduction to The Best Online Slots

One-armed bandits, fruit machines, and video slots; there are many names for this game commonly found at your online casino. Throughout this article, we’re going to take a deep dive into the world of online slots.

It can be hard to know where to start when learning about slots. If you’ve ever sat down hoping to play one of the best online slots with little to zero knowledge of the game, you’ve no doubt been overwhelmed with features, graphics, sound effects, and a whole load of bells and whistles.

While reels, rows and paylines are something you’ll find in every slot, one way or another, themes and complexity can vary greatly and range from ancient Egypt to Norse mythology to pirates, animals, crime, fantasy and traditional fruit or arcade styles.

We’re here to break this down for you, providing a safe knowledge base to go off and enjoy the best slots online. Let’s get down to it.

The Most Important Factors of Top Online Slots

So, you’ve decided that you want to play slots. Good choice. Slots have some of the most generous real money payouts that you’ll find at online casinos, and you don’t need a degree in applied algebra to play them. In fact, all you need to do is click ‘spin’, and the game does the rest for you.

That said, which game should you spin? Below are the most important factors to take into account when choosing an online slot.

RTP (Return to Player)

Many slot players rate RTP as the most important aspect of any slot. RTP, aka Return To Player, is the word employed by online casinos to describe the percentage a slot game returns over time. Let’s say you bet $1 on a slot with 95% RTP one hundred times. The laws of probability state you will get back $95 in winnings. This, in a nutshell, is RTP.

You might be wondering why anyone would essentially pay $100 to receive $95 back. Sounds like madness, we know. This brings us to the next most important factor to consider when choosing a slot – volatility.

Volatility in Online Slots

Also known as dispersion or variance, volatility defines the amount of risk (and some might say fun) in a particular slot game. Online slots come with volatility baked in. The three primary levels of volatility are low, medium, and high. You’ll also encounter slots with low-to-medium and medium-to-high volatility.

The lower the volatility, the more frequent your wins are, however, of a lesser value while your losses are less frequent too. Low volatility online slots are more like a gentle stroll in your local park. On the other hand, high volatility slots are closer to a rollercoaster ride where you’ll experience less frequent wins of a higher value and greater losses.

The only way to know which level of volatility you enjoy playing is to play a variety of the best online slots and find out for yourself how volatile you like your game. One of the best things about online slots is that there are always free play options available, meaning you don’t have to lose genuine funds while scoping out the perfect game for you.

Deposit Limits

Deposit limits are set by casinos rather than individual slot games. While each slot has its minimum and maximum wager threshold, deposit limits are enforced by operators. While a recent report published by the Social Market Foundation suggesting a mandatory cap on wagers, this has, so far, not been upheld.

Deposit limits are one of the many online casino factors overseen by the UK Gambling Commission (UKGC). The organisation ensures safe gambling, both online and in land-based casinos.

Jackpots

Many people are drawn to playing online slots by stories of players hitting the big time and taking down a jackpot prize. As in the case of 26-year-old Brit, Jon Heywood, who in 2015 scooped a $13.2 million prize from a 25p spin on one of the best online casino slots, Mega Moolah from Microgaming. It’s even in the Guinness Book of World Records.

Mega Moolah Wallpaper

Jackpot prizes are often called progressives or progressive jackpots. Progressive jackpots are thus named as they become progressively bigger each time a player plays the game, with a proportion of the wager being added to the jackpot total with each spin.

But, all jackpots are not born equally. Let’s take a look at the two different types of slot jackpots available at online casinos that could have you chuckling all the way to the building society.

Network Progressive Jackpots

Jon Heywood, the UK slots winner, became a multi-millionaire on this kind of jackpot slot. Much as it says on the tin: the jackpot is only available on specific networks, or to put it another way, on certain games. These network jackpots are played across various casinos – as opposed to operator-specific pots.

The Microgaming Mega Moolah series is a classic example of the best online casino slots in the network jackpots world. Other notable network progressive jackpots come courtesy of game providers NetEnt, BetSoft and Yggdrasil.

Local Progressive Jackpots

Local progressives are hosted by online casinos rather than game providers. The jackpot is usually on the lower side since it is only funded by players from a specific online casino. Local jackpot prizes can be rolled out by the casino or are funded by player deposits going up to tens of thousands of pounds in the most generous of cases.

When an online casino offers a local progressive prize, these are funded by players taking part in particular promotions hosted by this operator and the jackpots are created from entry tickets or wagering across a set of predetermined games, known as the game collection. The winner is sometimes the player that wagers the most across the game collection, a player who unlocks an in-game spin combination or the player who wins the most from a single spin at a set amount.

Online casinos offer many local jackpots during the holiday season, for instance, a busy time for the best online slots offers.

Random Number Generator (RNG)

The Random Number Generator (RNG) is the algorithm that produces random numbers and is employed by casinos to power all games, including all the best slots online. The RNG ensures all gaming outcomes are fair and completely random.

While you will find the occasional player complaining that some casino’s RNGs are rigged, this is a complete fallacy. All UKGC licensed casinos are highly regulated, and casino RNGs are fully compliant and above board. To further support gaming in a safe environment, independent institutions such as eCogra and iTech Labs work closely with online casinos to rule out any tampering with online slot machines.

Guiding You to The Best Online Slots

As mentioned, slots can come with many extra features. Whether you like your online slot jam-packed with features or more of a sedate affair is down to personal preference. One thing that all players seem to agree with though is the love of a Free Spins feature – more on this shortly. Coming up are the most important features that you should look out for when searching for the best online slots.

Reels and Paylines

The reels are the vertical column showing on a slot grid. Each adorned with its own unique set of symbols, these’ spin’ usually numbering about 20. Most classic slots have five reels, whereas more old-school fruity-style slots come with three reels.

Paylines are invisible lines on a slot grid where if you land certain symbol combinations, you win. Online slots range from having a single payline all the way up to 243 and even 117,649 different paylines in Megaways slots. Again, depending on whether you want your slot gameplay more frenetic or placid, paylines are a decisive factor.

Paylines can be fixed or variable. For each payline, you pay an additional wager. So, if you select 10 paylines at 20p per spin, you’ll be wagering a total of £2 per spin.

Wilds

Wilds are a common feature of online slot games, and most come with these as standard. If you’ve ever played poker with a wild card, slot wilds function in much the same way – by replacing other symbols similar to the joker in a 52-card deck. Wilds come in different shapes and sizes, so let’s knuckle down and take a closer look at exactly what kind of wilds you can expect while playing the best online casino slots.

Type Feature
Sticky Wilds Sticky wilds are a feature of pretty much every slot. They are everywhere. Sticky wilds are wilds that stay in place for an extra spin or more, giving players more opportunities for wins.
Transferring Wilds These wilds function by spreading across reels and are usually found in slots hosting a large number of reels.
Walking Wilds Similar to transferring wilds, walking wilds move on to other reels for subsequent spins but move along at a single reel each time.
Expanding Wilds These wilds expand vertically over the length of the reels, giving players even more chances to win with reel-wide wilds.

Scatters Symbols

Often known as a slot player’s best friend, scatters can appear anywhere on a slot grid and usually trigger free spin rounds or activate other bonus features. Scatters often take the logo image of the slot game itself, as they’re so integral to slot play.

Respins

Respins are a feature that, if you almost complete a winning combination, get another crack at the whip. Respins allow players to select a single reel to spin again and hopefully land the symbol of their dreams.

Free Spins and Online Slots

As the name suggests, free spins are gratuitous spins of a slot where you don’t have to pay any money. Free spin rounds can be triggered in numerous ways, most commonly by landing a certain combination or landing a specific symbol (usually scatters) several times. The number of free spins awarded will vary depending on which game you’re playing and the method of unlocking the free spin round.

Retriggers

If the RNG is favourable to you, you could encounter retriggers during a free spins round. A retrigger is an additional spin or spins during the free spin bonus round. You can always think of retriggers as a freebie on top of another freebie.

Multipliers

Multiplier symbols multiply your winnings by a certain amount. Specific symbols within a game represent multipliers and often take the form of the game’s protagonist(s). Multipliers range from 1x and can multiply winnings up to thousands of times.

Bonus Games

Bonus games are games within a game. These can be unlocked by landing certain combos in a slot’s base game. Once you’ve engaged with the bonus game (and hopefully taken down some cash on the way), you’ll return to the base game.

Bonus games come in many forms; they could come as a ‘flip ’em and see’ feature whereby players need to guess a certain card, or perhaps there’s a button-bashing element to the bonus game. Like the core game, all bonus games are powered by an RNG. Jackpot wheels and pick & click games are also mainstays of the slot bonus game world.

Gamble Feature

Gamble features are usually a coin flip-style game where players can wager their winnings in the hope of a double up. Choose wisely, and you’re looking at twice your in-game funds; choose poorly, and you’ll be leaving with nothing.

Cascading Reels

Instead of the traditional reels set up seen on analogue slot machines found in your local pub and used by many video slots, cascading reels are a completely different affair. Cascading reels render as falling flat symbols rather than spins. Once you hit a winning combination, the symbols disappear, allowing new symbols and further potential wins. This principle is also known as avalanche, tumbling reels, collapsing reels, or rolling reels.

Best Payout Online Slots

As we know, RTP is the basis of your expected winnings within a game over the long term. RTP hovers around the 96% mark in most slot games but can sometimes be as high as 99%. While a high RTP is indeed an aspect that most players use to gauge the value of a game, it’s not 100% decisive in whether you’ll win or not.

RTP balances out during hundreds of hours of play, so even if your chosen slot has a high RTP, you’re not guaranteed to win during a short gaming session. That said, here’s a list of the slots with the highest RTPs known to humankind.

Slot Title RTP
The Catfather 98.1 %

Best Time to Play Slots?

Is there a best time to play slots? Good question. When discussing online casino play, the short answer is no; there isn’t the best time to play slots. However, if you’re at a land-based casino, you might hear the terms ‘hot’ and ‘cold’ slots. A ‘hot’ slot is about to burst, and a ‘cold’ slot is the opposite. Remember that a payout is never guaranteed, no matter the ‘hot’ or ‘cold’ label. Busier periods might be the best time to play slots, though, as the physical machines will have a higher balance and higher potential winnings.

A progressive slot that’s reaching a high jackpot amount isn’t indicative of a slot win but can be used as a way of assessing the long term potential of a win. If a slot jackpot has reached a value that’s higher than ever, it could very well be the best time to play slots. Not only are you looking at a juicy prize, but the long term maths model will be reaching its average.

While there are mountains of slot strategy guides, these are usually not worth their weight on paper. Mostly concerned with bankroll management and how to spot ‘hot’ slots, they will only bring minimal value to your overall slots game.

Put simply, there’s no best time of day to play slots, but there is the best time to choose a slot to play – when the jackpot looks ready to drop.

Best Online Slots Offers

While shopping around for the best slots to play online, you’ll no doubt be amazed at all the promotions on offer from online casinos. These can range from welcome packages to themed campaigns. While these are great at getting more play from your money, they all come with promotion-specific terms attached. Let’s look at a few of the offers and conditions you’re likely to encounter when searching for the best slots online promotions.

Free Spin Offers

Often coming as a part of a casino welcome bonus package, free spin offers are complimentary spins awarded to players that deposit a certain amount or simply open an account. The minimum deposit to unlock such an offer ranges between $10 and $20. After adding the amount to your player account, you will automatically receive the free spins, which can be used on either one specific online slot or across the entire range of games available.

Deposit Offers

Deposit offers work in much the same way as free spin offers. With a deposit offer, players are given the option to deposit a certain amount in return for bonus money to be added to their accounts. Deposit offers are either given in full on your first deposit or tiered across the first two or three deposits.

The most common deposit offer is something like ‘100% Bonus up to $200′, which means you can double your deposit up to the maximum threshold.

The Rest of the Best Online Slots Offers

Casinos often give players the chance to take part in operator-specific promotions such as leaderboards, races, tournaments, challenges and missions. Each casino has its own calendar and spin on these promos, so it’s worth doing a bit of window shopping before embarking on an offer.

Terms & Conditions for Slot Offers

The bible for online casino players, T&Cs should be scrutinised before embarking on your online casino offer.

Bonus Restrictions

Wagering Requirement

The wagering requirement is the most important key term to take into account before entering into a promotion. Also called a rollover or playthrough, the wagering requirement is the number of times you need to wager your winnings from bonus amounts or free spins before you can withdraw them.

Wagering requirements vary from 1x (usually reserved for high-value or VIP players) but can reach up to 60x. The average seems to be around 35x to 40x, which is an acceptable amount. Any higher, and it’s a sign that the casino is not being as generous as it could be.

If you do not complete your wagering requirement in the allotted time frame, you will lose all winnings associated with your bonus. It’s also worth remembering that you will lose your bonus funds if you withdraw your bonus balance before the wagering is completed.

Time Limit

A time limit is usually always applied to promotional offers, both free spins and deposit offers. This ensures that players wager more during a time period. If you haven’t completed your wagering requirement or used your free spins during the period, you will lose your bonus.

While these special terms can easily feel unfair, it’s important to remember that they only apply to bonus funds. It’s a way for the casino to combat abuse, which is common in online gambling. The moment you play with real money, you won’t have to meet any wagering requirements or obey time limits to withdraw your winnings.

Well-known Slot Game Developers

The genius behind your favourite slots is the game developers. These casino software companies are teams of designers, game architects, mathematicians, and project managers, who release more than a dozen slots are each week.

With this sheer amount of available games, it’s important to have websites like use review providers and their slots and make all information accessible to you. Here are some of the best companies in the industry. For a complete overview, head over to our page on casino software providers.

NetEnt

Swedish slot supremos NetEnt have been in the game for over 20 years and are responsible for some of the biggest and best slots to play online. Titles include the smash hit Gonzo’s Quest, the online casino lobby favourite Starburst, and the western-themed Dead or Alive and Dead or Alive 2.

Widely considered as having the best graphics teams on the slot development planet, NetEnt is both old hands and pioneering slot makers. Now they are a part of the Evolution Gaming group alongside game producers Red Tiger.

Microgaming

Based on the Isle of Man, Microgaming has the largest progressive jackpot network globally and has paid out over $1 billion in prizes to date. Releases include Jurassic Park™, Game of Thrones™, Book of Oz, and the ‘millionaire-maker Mega Moolah.

Microgaming Logo

Microgaming is one of the founding members of eCOGRA, an organisation dedicated to the standard of fair, responsible gaming.

Big Time Gaming (BTG)

Standing for Big Time Gaming or Inventors of the ‘Megaways’ mechanic, with 17,649 ways to win, BTG is the relatively new kid on the block. Established in 2011 and responsible for game titles that include Monopoly Megaways, Opal Fruits, and Book of Gods, BTG are still to make their mark but are a game provider making waves. Both original and dynamic, BTG is a provider to keep an eye on.

Quickspin

Based out of Stockholm and active since 2011, three chaps set up one of the most forward-thinking gaming companies around today. Ahead of the curve, they produced blockbuster titles that include Big Bad Wolf Megaways, Eastern Emeralds, and Dwarfs Gone Wild.

Quickspin Logo

In 2016, Quickspin was acquired by gaming behemoth Playtech, probably one of the world’s biggest online gaming software suppliers.

Push Gaming

Providers of premium quality casino games, Push Gaming’s talent doesn’t start and end with video slots. Committed to delivering quality games and teaming up with talented partners, they’re tight with the biggest online casino operators in iGaming.

Push Gaming is home to some of the best slots to play online such as Booty Bay, Fat Rabbit, and Jammin’ Jars.

FAQ

What are the best online slots to play?

It depends on the type of player you are, but titles like Wolf Gold, 9 Pots Of Gold and Big Bass Bonanza have been trending this year. Go back up to look through our list of top slots by providers.

Which are the top real money slots?

Playing for real money is when online slots really come to life. While you should generally look for high RTP slots, there are other factors to consider when looking for the best real money slots. Check out our guide on this topic to learn more.

What are the best online slot companies?

Many providers have released high-quality games, so it’s difficult to pick that one slot company that beats them all. Big Time Gaming, Play’n GO, Push Gaming, and Pragmatic Play have certainly been pushing the bar high this year. Here is a list of all the top providers and their games.

When is the Best Time to Play Online Slots?

To be completely honest with you, there isn’t the best time to play online slots. You might have heard of terminology like ‘cold slots’ and ‘hot slots’, but don’t get sucked into some conspiracy theories. Predicting a win is not possible, and you should not rely on the ‘rubbing the crystal ball’ strategy; it’s not worth it in the end.

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