Guide to the Best Online Slots Machines in 2021
At online.casino, we have the biggest and best range of video slots and classic games to play for free. Whether you’re looking for 3-reel games or the latest 5-reel slots with big bonuses, we have it covered.
On this page, you can discover a world of real money slots from the most popular developers. We’ll even recommend the best online casinos where you can begin playing in seconds.
Read our guide to find online slots for real money:
- Discover the best slots from the world’s biggest developers
- Learn how to win more playing slots on your PC and mobile
- Unearth some top slot casinos with our expert reviews
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What are Online Slots?
An online slot is a casino game that pays out prizes depending on the arrangement of symbols on a series of reels.
Most online slots resemble video slot machines you will find in a land-based casino. The difference is you can play on your PC or mobile device.
Essentially, online slots work in the same way as physical slot machines: you select your stakes and spin a series of reels containing symbols. You win prizes according to the arrangement of symbols on a horizontal payline. The more symbols you match, the more you win.
There are thousands of slot games available in 2021. You can try your luck with classic 3-reel games with minimal paylines or up the action by playing 4,096 ways to win on a 6-reel slot.
Navigating the world of best online slots can be tricky. There are thousands of games from dozens of developers, all with their own bonus features and payouts. And not all online casinos offer the same games.
That’s where we come in. At online.casino, we root out the top casino sites with the most reliable and best-paying slots on the web.
Free Online Casino Slots (2880)
Finding the Best Slots Casinos in 2021
To play online slots, you need a great online casino. Our team tests and reviews dozens of casinos to find you the best deals and games. Here are the criteria we use:
- Great Range of Games: The best casinos have hundreds of games from a range of leading providers. You can also play a comparable selection of games on your Apple or Android device.
- The Best Return-to-Player Percentages: Every slot has its own RTP (Return-to-Player percentage). We check every casino’s audit certificate to make sure its RTPs stack up.
- Top Safety & Security: Every reputable casino online should have audited slots and the latest SSL encryption to protect players’ data and funds.
- The Best Slot Bonuses & Promotions: You can claim a deposit match bonus or free spins when you sign up to a top casino. We closely check the terms and conditions of every casino slots bonus.
- The Biggest Software Providers: There are dozens of software providers producing slots for online casinos. But how do you know which developers are trustworthy and provide the best games.
Slots Providers & Game StudiosSee All
At online.casino, we will never recommend a site that has unlicensed software providers. All of our top-rated casinos have games from properly licensed and audited developers. Here are 8 of the best:
Top online slots: Gonzo’s Quest, Starburst, Aliens, The Invisible Man
NetEnt is an award-winning Scandinavian developer that produces slots for many online casinos. The developer has licenses in reputable jurisdictions like Malta, Gibraltar, and New Jersey, and is known for its slick bonus features and branded slots.
Top online slots: Mega Moolah, Thunderstruck, Major Millions
UK developer Microgaming was the first to release an online slot back in the mid-1990s.Since then, Microgaming has released hundreds of games, including the record-breaking progressive slot, Mega Moolah.
Top online slots: Age of the Gods, Beach Party, Football Star
Founded in 1999 by Teddy Sagi, Playtech produces slots and platforms for many of the leading online casinos today. Playtech was behind the successful Marvel slots before they were withdrawn in 2013. However, the developer continues to produce excellent 5-reel slots and branded games.
IGT/International Gaming Technology
Top online slots: Cleopatra, Siberian Storm, Wheel of Fortune
IGT is a US legend in the slots industry. They began as a producer of land-based slot machines before moving into the online slots business. IGT continues to produce slick slots for online and offline casinos.
Top online slots: 2 Million BC, A Night in Paris, Black Gold
BetSoft is a world leader in producing 3D slots and immersive games. BetSoft slots are known for slick, animated graphics and innovative bonus features.
Top online slots: 50 Dragons, Dolphin Treasure, Miss Kitty
Aristocrat is one of Australia’s largest producers of online slots and land-based “pokies.” Aristocrat games can be found in casinos and pubs all across Australasia.
Top online slots: Quick Hit Platinum, Triple Cash Wheel, Monopoly Heights
Along with IGT, Bally is one of the USA’s biggest slots developers. It also forms part of the giant, Scientific Games. Bally is responsible for hundreds of online slots adapted from successful land-based games like Hot Shot Progressive, Anchorman, and MONOPOLY 250k.
WMS/Williams Interactive Software
Top online slots: Bruce Lee, Invaders from the Planet Moolah, Spartacus Call to Arms
WMS is a US provider that produces slots for land-based and online casinos. It’s also part of the Scientific Games group and is known for its Colossal Reels range of slots.
There are many smaller game studios that also produce quality slots. One great example is Wazdan, a Malta-based game studio with a growing audience.
How Online Slots Work: Our Top Guide
Learning to play video slots online is easy, but because there are so many types of casino games available, it can be tricky to choose which ones to play. Let’s run down the kinds of online slots you will find at some of our top-rated casinos. Also, see our guide on how to play slots.
Types of Real Money Online Casino Slots
When slot machines were first invented in the late 19th-century, they were mechanical beasts with just a few primitive settings.
The world of online slots is very different now. These days, you can choose from a massive range of games online with features to suit every taste.
3-Reel: 3-reel slots have a trio of vertical reels that spin at random. Typically, 3-reel slots feature one to five paylines running horizontally across rows. Bonus features tend to be minimal, but you might find a basic wild symbol included on the reels.
Classic: Classic slots evoke the old-school machines you might have found in a Las Vegas casino in the early 20th-century.
Classic slots usually feature traditional slot symbols like fruit, bells and BAR icons. They will also come accompanied by the traditional sound effects of a one-armed bandit.
5-Reel: Most modern online slots come with five reels. There may be three or four rows featured too. The benefit of having five reels is that more paylines are made possible.
Typically, a 5-reel slot will have 10-50 paylines. Many 5-reel slots can handle up to 1,024 possible paylines.
Multiway Slots: The advance of online slots software means many games can cope with a lot more paylines.
Multiway slots work differently from traditional 5-reel games. You win a prize simply by matching symbols anywhere on adjacent reels.
Instead of paylines, you win by landing symbols on ‘ways to win.’ Multiway slots can feature anywhere from 243 to 4,096 ways to win. Special bonus features can enlarge the reels to fit in over 100,000 ways to win.
Bonus Slots: Most online slots have at least one bonus feature. Bonuses can be as simple as a free spins round or paying wild symbol.
More complex bonuses can feature progressive win multipliers that increase the more you win. Some games have immersive storylines where you can save your position to revisit later.
3D Slots: With today’s powerful online slots, you can enjoy better graphics and a better overall user experience.
Some developers specialize in 3D slots that feature animated symbols and cutaway sequences, cinematic soundtracks, and realistic characters. 3D slots can also contain innovative bonus features you just won’t find in regular 5-reel games.
Progressive Slots: A progressive slot features a linked jackpot made up of portions of every player’s bet. You can trigger the jackpot by activating a special bonus feature or game.
The most popular progressive slots might have jackpots that run into millions of dollars. The more people who play, the larger the jackpot gets. At online.casino, we recommend the very best casinos with the biggest progressives.
The Best Slots Bonus Features Explained
Many of the best casino slots feature some kind of bonus. Let’s take a closer look at some of the features you’ll find in our top-rated gambling slots.
Wild symbols: Wild symbols act like jokers that fill in the gaps in winning combinations. They usually come with some kind of multiplier attached too. You might double your win by using a wild in a winning combo.
Scatters: Scatter pays are symbols that award prizes regardless of where they land. You win by having a scatter in view anywhere on the reels. Scatters are also responsible for triggering bonus features like free spins.
Walking Wilds: Walking wilds are appearing in more and more real money slots. When one appears, it will lock in place and shift one reel to the left after each subsequent spin.
Transferring Wilds: Transferring wilds and replicating wilds make copies of themselves to create bigger wins. In an online slot with more than one set of reels, transferring wilds can also be copied from one reel set to another.
Free Spins: Free spins is the most common form of slots bonus. You usually win free games by landing enough qualifying scatters on the reels.
Tumbling Reels: Tumbling Reels is a feature used by the leading slots developers. It’s also known as Cascading Reels or Avalanche Reels.
After a winning spin, the symbols involved disappear, to be replaced by those sitting above on the reels. More winning combinations can then be created.
Some Tumbling Reels slots feature a progressive multiplier. This increases every time a new winning combination is formed.
Split Symbols: Split symbols appear in some classic and modern 5-reel slots. Split symbols act as pairs when determining a payout. In a 5-reel slot, therefore, it’s possible to hit not five but ten winning symbols on a single payline.
Gamble Feature: Many older classic slots feature a gamble bonus. The gamble feature gives you the chance to double your money by playing a bonus game. It might involve guessing the color of the next card drawn or taking part in a high-low game.
Real Money Slots vs Play Money Slots
The beauty of online casinos is that you can try before you buy. At our top-rated casinos, you can try hundreds of games for free or real money. Both types of games have their own benefits and drawbacks:
Test a game with no financial risk: With free-play slots, you can try out a game without risking your bankroll, which is the case with slots for real money. Test a new developer or try a brand new release to see if you enjoy the gameplay and theme.
Try out a game’s volatility: Volatility relates to the frequency with which a slot pays out. Not all slots online pay with the same regularity.
Some slots pay little and often, while others pay well but infrequently. By testing slots for free, you can get an idea of which is which.
Play at low stakes or big money: You can play slots for real money at a wide range of stakes. Choose to wager a few cents or hit the Max Bet button and spin for hundreds of dollars.
The beauty of online casino slots is that you have full control over your stakes. That’s one benefit online casino games have over land-based games.
Take a shot at a progressive jackpot: With real money slots, you can try to win a linked progressive jackpot. The higher your stakes, the more chances you have to win.
Clear a casino welcome bonus: Real money slots play is great for claiming a welcome bonus promotion. You can claim free cash by playing your favorite slots during your first week or month.
At online.casino, we only recommend the best slots casinos that have generous and realistic welcome bonus offers.
The Best Online Slots to Play in 2021
Each online casino might have hundreds of different slots to play. So what games do you go for, and which have the best rate of return?
At online.casino, you will find some of the finest slots with the best odds and returns. Let’s round up 10 of our favorite online gambling slots to play in 2021.
1. Starburst (NetEnt)
Starburst is a space-themed slot popular with casino bonus hunters all over the world. This low-variance slot has expanding wilds that can improve your payouts.
2. Mega Moolah (Microgaming)
Microgaming’s record-breaking progressive slot has awarded tens of millions in payouts during its lifetime. The nature-themed slot also boasts a lucrative free spins bonus.
3. Mega Fortune (NetEnt)
NetEnt’s Mega Fortune once held the world-record for a progressive jackpot — around 15 million Euros. The millionaire-themed slot features three levels of progressive.
4. Cleopatra (IGT)
IGT’s timeless Egyptian-themed slot is popular among land-based and online slots players alike. There is also a MegaJackpots Cleopatra edition with a giant progressive jackpot.
5. Ugga Bugga (Playtech)
Ugga Bugga is a 3-reel online slot like no other. Every time you spin one set of reels, the symbols are replicated across the remaining 9. You can hold symbols of your choice for a chance of winning big payouts.
6. Mega Joker (NetEnt)
Mega Joker is one of the best classic slots available online. The game works on two sets of reels. A lower reel set is used in the base game, and the upper set triggers every time you hit a winning spin.
7. Rainbow Riches Pick ‘n Mix (Barcrest)
Barcrest’s range of Rainbow Riches slots is popular with players everywhere. Rainbow Riches Pick ‘n Mix features a prize wheel, free spins, and a pick ’em bonus.
8. Age of the Gods (Playtech)
When Playtech was forced to shut its Marvel Super Heroes range, the developer kept the software but changed the names of the games. Age of the Gods was the first in the series and features a massive progressive jackpot.
9. Pharaoh’s Secrets (Playtech)
Playtech’s Egyptian-themed slots feature the XtraWin bonus which turns every wild symbol into an expanding wild. It’s a volatile slot with a lot of action.
10. After Night Falls (BetSoft)
After Night Falls is a great example of BetSoft’s 3D slot engine. The crime-themed slot features superb animation and a lot of big bonus features.
Want more? Discover our leading online slots reviews and find a game that’s right for you.
Top 5 Online Slot Tips
Now you know how to find great online slots and the top casinos that feature them. Get your slots adventure off to the best possible start with our tips.
1. Read our slots reviews and try before you buy
There are thousands of slot casino games out there. Luckily, you can play many games for free before committing a bankroll. Read our expert reviews and play for free first.
2. Don’t dismiss classic online slots
Most modern slot games are 5-reel games with one or two bonus features. Don’t dismiss the classic slots, though. Classic games and 3-reel slots are quick to play and oftentimes have a lower variance.
3. Take a shot at a progressive jackpot
A progressive slot can offer the chance of a life-changing prize payout. You will oftentimes have to bet the maximum to be eligible to win. Save some bankroll and take a shot.
4. Read the paytable every time
Every video slot has a paytable listing payouts, bonus details, and RTP. Always read the table before you spin the reels. You can gauge whether a slot is volatile and whether the long-term payouts are good.
5. Only trust reputable casinos online
Most online casinos offer slot games, but not all casinos are trustworthy. Only sign up with the most reliable casinos with audited software and verified payouts. You will find a selection of the best sites at online.casino.
Unearth the Best Online Slots & Casinos
In 2021, you can take your pick of thousands of slots of all themes and colors. You can choose from an old-school classic slot or risk your bankroll on a million-dollar progressive.
At online.casino, we only recommend the very best selection of games and casinos. With our exclusive links you can try slots for free before signing up to one of our top-rated sites.
Claim your slots welcome bonus today and earn real cash playing the games you love.