Top 100 Australia Online Casinos for 2026: The Complete Ranking

Australia's online casino landscape is unusual: the Interactive Gambling Act 2001 prevents companies from operating or advertising real-money online casinos locally, but the law targets operators, not players. As a result, Australian players access offshore-licensed casinos under international frameworks — typically Curaçao, Anjouan or Costa Rica — that serve the Australian market with AUD support, PayID and POLi rails. This guide ranks the top 100 Australia online casinos for 2026, structured as a full top-100 leaderboard with the top 20 profiled in detail and the remaining 80 grouped by tier. The evaluation focuses on AUD-native cashiers, PayID and POLi integration, licence strength, mobile experience, and the transparency of RTP figures for pokie titles.

How This Top 100 Was Ranked

Five criteria drive the ranking. Licensing strength distinguishes tier-1 offshore regulators (Malta Gaming Authority, Isle of Man) from tier-2 (Curaçao master licences, Anjouan) and tier-3 (unclear or unverifiable licences). Payment infrastructure gives priority to AUD-native cashiers with PayID and POLi integration over operators that force currency conversion. Withdrawal speed is measured in the documented processing window for a verified account. Pokie catalogue depth is measured by title count and provider diversity, with weighting for RTP transparency. Mobile experience is evaluated on native app quality (Android APK, iOS via TestFlight or direct install) and responsive-web parity.

#1. Golden Crown Casino

Golden Crown is consistently rated as the most trusted and safest Australian-facing online casino across independent 2026 review sources. The operator offers strong offshore licensing, AUD-native cashier with PayID and POLi, and a broad pokie catalogue. Golden Crown's welcome bonus programme is competitive without carrying restrictive terms, and the withdrawal window for verified accounts is among the shortest in the Australian offshore segment.

#2. LuckyVibe Casino

LuckyVibe is the top-ranked Australian option for online pokies specifically. The operator focuses its catalogue on the highest-RTP slots (96-98%) with a large title count from providers including Pragmatic Play, NetEnt, Play'n GO and Push Gaming. AUD support, PayID and POLi are integrated, and the site emphasises fast withdrawals for verified accounts.

#3. SkyCrown Casino

SkyCrown is the leading destination for jackpot chasers in the Australian market, with a curated selection of progressive jackpot titles across multiple networks. Independent reviews rank SkyCrown highest for jackpot access among Australian-facing offshore casinos. AUD-native cashier and standard offshore payment rails.

#4. VipLuck Casino

VipLuck is rated as the best online casino for real money in Australia by several independent 2026 sources, offering the strongest combination of game variety, bonus value and fast payouts. The site accepts AUD deposits through PayID, POLi and crypto, and processes withdrawals within 24 hours for verified accounts.

#5. Rooster.bet Casino

Rooster.bet operates legally under international licences for the Australian market, offering a mixed casino and sportsbook experience. The pokie catalogue is competitive, AUD support is native, and the site includes a strong crypto payment layer alongside standard offshore rails.

#6. SlotsGem Casino

SlotsGem is a specialist Australian-facing pokie casino with strong offshore licensing and a broad title selection. AUD support, PayID and POLi rails, and a mobile-first delivery through Android APK plus iOS PWA.

#7. Spinjo Casino

Spinjo is a mid-tier Australian-facing offshore operator with competitive pokie catalogue, AUD-native cashier and integrated crypto payments (Bitcoin, USDT). Welcome bonus structure is transparent, and the responsive-web mobile version delivers the full desktop functionality.

#8. Rich Wilde Australia

Rich Wilde Australia is a specialist for high-RTP pokie players with a curated catalogue including the Book of Dead and Reactoonz series from Play'n GO alongside broader slot library. AUD support and PayID.

#9. Ricky Casino

Ricky Casino is a well-established Australian-facing offshore operator with a large pokie catalogue exceeding 3,000 titles. AUD support, standard offshore payment rails, and competitive welcome bonus structure.

#10. Kingmaker Casino

Kingmaker rounds out the top 10 with strong offshore licensing, a curated pokie catalogue and AUD-native cashier. The site includes a live-casino segment via Evolution alongside the core pokie offering.

#11. Playamo Casino

Playamo is a crypto-forward pokie casino with a strong AUD-native cashier and one of the most established Australian-facing brands in the segment. The site carries a broad Pragmatic Play, NetEnt and Yggdrasil catalogue, live-dealer tables via Evolution, and cryptocurrency deposits alongside PayID and cards. Withdrawal speeds are consistently among the top tier of Australian-facing operators.

#12. Wildz Casino

Wildz is a large multi-jurisdiction operator with an Australian-facing presence and a well-known Level Up gamification layer that rewards ongoing play with cashback and reload bonuses. The pokie library is deep, live-casino coverage runs through Evolution, and the mobile experience is optimised for Australian mobile networks.

#13. National Casino

National Casino is a broad-catalogue offshore casino with strong Australian localisation, AUD-native accounts and PayID rail support. The site emphasises weekly promotional rotation over a single large welcome bonus, and the cashier includes both traditional card methods and cryptocurrency.

#14. 22Bet Casino

22Bet operates as a combined sportsbook and casino with a deep pokie library alongside its established betting product. Australian players get AUD support, PayID and card options, and access to a large slot catalogue that draws from 40+ providers. Cryptocurrency support is layered on top of the fiat rails.

#15. Bizzo Casino

Bizzo is a mid-tier Australian-facing operator with strong Pragmatic Play and Play'n GO coverage, competitive weekly promotional structure and PayID support. The site targets recreational pokie players rather than high-rollers, and welcome bonus terms sit near the middle of the market.

#16. IviBet

IviBet is a sportsbook-plus-casino operator with growing Australian traction. The casino side runs a broad multi-provider catalogue with focus on Pragmatic Play, NetEnt and BGaming. AUD accounts and PayID withdrawals are supported.

#17. 20Bet Casino

20Bet offers a similar sportsbook-plus-casino profile to 22Bet with lighter branding. The pokie catalogue draws from the standard offshore multi-provider stack, AUD accounts are supported, and PayID and cryptocurrency deposit rails are available.

#18. Casinonic

Casinonic is a specialist AUD-native casino built for the Australian market from the ground up. The site's cashier is optimised for PayID and POLi, the welcome bonus targets Australian players specifically, and the pokie catalogue emphasises titles with strong Australian player recognition.

#19. Fair Go Casino

Fair Go is one of the longest-running Australian-facing operators with distinctive Australian-themed branding. The site is Realtime Gaming-focused, giving it a different provider profile from the mostly Pragmatic Play-led competitors, and it maintains strong AUD-native cashier support alongside card, bank transfer and cryptocurrency options.

#20. Uptown Pokies

Uptown Pokies rounds out the top 20 as a specialist pokie operator with an AUD-native cashier and a classic Australian pokie style. The Realtime Gaming catalogue provides depth in the pokie category with weekly reload bonuses and a straightforward VIP progression.

#21. Pokie Spins Casino

Pokie Spins is an Australian-themed pokie specialist with Realtime Gaming and BetSoft coverage, AUD-native cashier and PayID rail support. The site targets recreational pokie players with clear bonus terms and consistent weekly reload offers.

#22. Kahuna Casino

Kahuna Casino runs a broad multi-provider slot catalogue with Pragmatic Play, NetEnt and BGaming coverage. AUD accounts and cryptocurrency deposits sit alongside standard card and bank-transfer methods.

#23. Two-Up Casino

Two-Up leans into a distinctly Australian brand identity referencing the classic Two-Up coin game. Realtime Gaming pokie library with AUD-native cashier and standard offshore withdrawal windows.

#24. Ozwin Casino

Ozwin is a specialist Australian-facing operator with Realtime Gaming exclusivity and a strong welcome package structured around ongoing reload bonuses. AUD accounts, POLi and card support.

#25. Emu Casino

Emu Casino was one of the earliest dedicated Australian-facing offshore operators. Broad multi-provider slot catalogue, AUD-native cashier and a well-established VIP programme for regular players.

#26. Casino Mate

Casino Mate offers a Microgaming-focused slot library with access to the Mega Moolah progressive jackpot network. AUD accounts, standard offshore payment methods and a straightforward loyalty scheme.

#27. King Billy Casino

King Billy is a distinctive-branded offshore casino with an Australian-facing product, broad Pragmatic Play, NetEnt and BGaming coverage and a tiered VIP kingdom loyalty progression.

#28. Casino Room

Casino Room delivers a multi-provider slot catalogue with strong Australian-facing localisation. AUD-native cashier, PayID rail support and cryptocurrency deposit options alongside standard cards.

#29. Woo Casino

Woo Casino runs a broad slot library with Pragmatic Play and NetEnt anchors, competitive weekly promotional calendar and standard offshore withdrawal windows. AUD accounts and PayID supported.

#30. Zoome Casino

Zoome Casino delivers a mid-tier Australian-facing product with multi-provider slot coverage, AUD-native cashier and reliable PayID rail support for both deposits and withdrawals.

#31. Kajot Casino

Kajot Casino focuses on classic slot content from the Kajot studio alongside multi-provider third-party coverage. AUD accounts, standard offshore card and cryptocurrency methods.

#32. Betchan Casino

Betchan is an established Australian-facing operator with a broad slot library, competitive welcome bonus and standard offshore payment infrastructure including AUD-native accounts.

#33. Slotum Casino

Slotum Casino delivers slot-first branding with deep Pragmatic Play, NetEnt and Play'n GO coverage. AUD-native cashier and PayID support alongside cryptocurrency deposits.

#34. Katsubet Casino

Katsubet combines a Japanese-themed brand identity with a broad offshore slot catalogue and live-casino coverage via Evolution. AUD accounts and standard offshore withdrawal rails.

#35. Playzee Casino

Playzee is a mid-tier Australian-facing operator with multi-provider slot coverage, live-casino access and a straightforward welcome bonus. AUD-native cashier with PayID support.

#36. Winspark Casino

Winspark Casino delivers a broad multi-provider slot catalogue with focus on established European studios. AUD accounts, card and cryptocurrency deposit options.

#37. LevelUp Casino

LevelUp Casino uses a level-progression retention layer on top of a standard offshore slot catalogue. AUD-native cashier, PayID rail support and cryptocurrency deposits.

#38. Golden Star Casino

Golden Star Casino offers a broad multi-provider slot library alongside live-casino coverage. AUD accounts, PayID and cryptocurrency deposit rails available.

#39. Bao Casino

Bao Casino delivers an Asian-themed brand identity with broad slot coverage and cryptocurrency-friendly cashier alongside AUD-native accounts and standard card rails.

#40. Sportaza Casino

Sportaza pairs a sportsbook product with a casino offering, giving cross-vertical loyalty for Australian players interested in both segments. AUD accounts and PayID support.

#41. Mostbet Australia

Mostbet Australia is the Australian-facing arm of the Mostbet operator group. Broad slot library, sportsbook integration and AUD-native cashier with standard offshore payment methods.

#42. Betamo Casino

Betamo Casino runs a multi-provider slot catalogue with mid-tier welcome bonus and reliable AUD-native cashier. PayID and card rails alongside cryptocurrency support.

#43. GoWild Casino

GoWild Casino delivers an established brand with Microgaming coverage including Mega Moolah access. AUD accounts and standard offshore withdrawal windows.

#44. LOKI Casino

LOKI Casino uses a Norse-mythology brand identity on top of a broad offshore slot library. AUD-native cashier and cryptocurrency deposit rails alongside standard cards.

#45. House of Jack

House of Jack focuses specifically on the Australian market with an AUD-native cashier from the start. Broad multi-provider slot coverage and PayID support.

#46. Casino Universe

Casino Universe delivers a cosmic-themed brand identity with a broad slot library and reliable AUD-native cashier. Standard offshore payment infrastructure.

#47. JVSpin Casino

JVSpin Casino runs a multi-provider slot catalogue with mid-tier welcome bonus terms. AUD accounts, PayID rail support and cryptocurrency deposit options.

#48. Bitkingz Casino

Bitkingz Casino is a crypto-first offshore operator with strong Bitcoin and USDT support alongside AUD-native fiat accounts. Broad multi-provider slot coverage.

#49. Rolling Slots Casino

Rolling Slots delivers a slot-first Australian-facing product with broad Pragmatic Play, NetEnt and Play'n GO coverage. AUD accounts and standard offshore withdrawal windows.

#50. Golden Reels Casino

Golden Reels is an Australian-themed offshore operator with strong AUD-native cashier support and a broad multi-provider slot library including live-casino via Evolution.

#51. Ridika Casino

Ridika Casino delivers a mid-tier Australian-facing product with multi-provider slot coverage and standard offshore payment methods including AUD accounts and cryptocurrency.

#52. Freshbet Casino

Freshbet pairs a sportsbook with a casino product, giving cross-vertical account structure. Broad slot library, AUD accounts and PayID rail support.

#53. Rabona Casino

Rabona Casino uses a football-themed brand identity across sportsbook and casino verticals. Multi-provider slot coverage and AUD-native cashier for the Australian market.

#54. Betsson AU

Betsson AU is the Australian-facing arm of the Betsson group, delivering strong pan-European operator experience with AUD accounts and broad slot coverage.

#55. Yoju Casino

Yoju Casino delivers a broad multi-provider slot library with mid-tier welcome bonus terms. AUD-native cashier and cryptocurrency deposits alongside standard cards.

#56. Alf Casino

Alf Casino uses a distinctive character-driven brand identity on top of a broad offshore slot library. AUD accounts and PayID rail support.

#57. MyStake Casino

MyStake Casino combines casino and sportsbook verticals with strong cryptocurrency support alongside AUD-native fiat accounts. Broad multi-provider slot coverage.

#58. Boomerang Casino

Boomerang Casino leans into an Australian-themed brand identity with AUD-native cashier and a broad multi-provider slot library targeting recreational pokie players.

#59. Vulkan Vegas

Vulkan Vegas delivers an established multi-provider slot library with strong European operator heritage adapted for Australian-facing play. AUD accounts and standard offshore rails.

#60. Malina Casino

Malina Casino offers a broad slot library with mid-tier welcome bonus and reliable AUD-native cashier. Standard offshore payment infrastructure including cryptocurrency.

#61. Sol Casino

Sol Casino uses a sun-themed brand identity with broad multi-provider slot coverage. AUD-native cashier, PayID and cryptocurrency deposit rails.

#62. Mr Bet Casino

Mr Bet Casino is an established multi-market operator with Australian-facing product. Broad slot library, AUD accounts and standard offshore withdrawal windows.

#63. 7BitCasino

7BitCasino is a crypto-first offshore operator with strong Bitcoin, USDT and Ethereum support alongside AUD-native fiat accounts. Long-established Australian-facing presence.

#64. MBit Casino

MBit Casino is a crypto-focused offshore casino with broad multi-provider slot coverage. AUD accounts alongside Bitcoin, USDT and Ethereum deposit and withdrawal rails.

#65. BitStarz Australia

BitStarz is one of the most established crypto-friendly offshore casinos with strong Australian-facing presence. Broad multi-provider slot coverage and AUD-native fiat accounts.

#66. FortuneJack Casino

FortuneJack is a crypto-first offshore casino with broad slot coverage and strong sportsbook integration. AUD accounts alongside Bitcoin and altcoin deposit rails.

#67. WildTornado Casino

WildTornado Casino delivers a broad multi-provider slot library with cryptocurrency-friendly cashier alongside AUD-native fiat accounts and PayID rail support.

#68. N1 Casino

N1 Casino is part of the N1 Interactive brand family with broad Australian-facing product. Multi-provider slot library, AUD accounts and standard offshore payment methods.

#69. Slotocash Casino

Slotocash Casino is a long-established Realtime Gaming-focused offshore casino with strong Australian-facing presence. AUD-native cashier and standard offshore withdrawal windows.

#70. Aussie Play Casino

Aussie Play targets the Australian market specifically with Realtime Gaming pokie coverage, AUD-native cashier and a straightforward welcome bonus structure.

#71. King Neptunes Casino

King Neptunes Casino runs a Microgaming-focused slot library with access to the Mega Moolah progressive network. AUD accounts and standard offshore payment methods.

#72. Roaring 21 Casino

Roaring 21 uses a 1920s-themed brand identity on top of a Realtime Gaming slot library. Long-established Australian-facing operator with AUD-native cashier.

#73. Slots Empire Casino

Slots Empire Casino delivers a Realtime Gaming-focused slot library with strong Australian-facing localisation. AUD accounts, standard card and cryptocurrency methods.

#74. Red Dog Casino

Red Dog Casino is a Realtime Gaming-focused offshore casino with distinctive canine-themed branding. AUD-native cashier and reliable weekly promotional calendar.

#75. El Royale Casino

El Royale Casino uses an Art Deco-themed brand identity on top of a Realtime Gaming slot library. AUD accounts and standard offshore withdrawal windows.

#76. Cocoa Casino

Cocoa Casino delivers a Realtime Gaming-focused slot library with strong Australian-facing product. AUD-native cashier and consistent weekly reload bonus structure.

#77. Miami Club Casino

Miami Club Casino is a long-established WGS Technology-focused offshore casino with Australian-facing product. AUD accounts and reliable withdrawal windows.

#78. Vegas Rush Casino

Vegas Rush Casino uses a Vegas-themed brand identity with Realtime Gaming slot coverage. AUD-native cashier and standard offshore payment methods for the Australian market.

#79. Jackpot Wheel Casino

Jackpot Wheel Casino delivers a Saucify and Betsoft-focused slot library with strong Australian-facing product. AUD accounts and standard offshore withdrawal windows.

#80. Grand Rush Casino

Grand Rush Casino runs a broad multi-provider slot library with mid-tier welcome bonus. AUD-native cashier and reliable weekly promotional structure.

#81. True Blue Casino

True Blue Casino uses a distinctly Australian brand identity with Realtime Gaming slot coverage. AUD-native cashier and consistent Australian-facing operator reliability.

#82. Pokie Place Casino

Pokie Place Casino targets the Australian pokie player specifically with Realtime Gaming coverage, AUD-native cashier and reliable weekly reload bonuses.

#83. Aussie Casino Club

Aussie Casino Club delivers a broad multi-provider slot library with Australian-facing product. AUD accounts and PayID rail support alongside standard cards.

#84. Tangiers Casino

Tangiers Casino uses a Moroccan-themed brand identity on top of a broad slot library. Australian-facing operator with AUD-native cashier.

#85. Casino Superlines

Casino Superlines delivers a broad multi-provider slot library with mid-tier welcome bonus. AUD accounts and standard offshore payment methods.

#86. Winner's Magic Casino

Winner's Magic Casino runs a broad slot library with reliable AUD-native cashier. Standard offshore payment methods alongside cryptocurrency support.

#87. Casino-X

Casino-X is an established multi-provider slot casino with Australian-facing product. AUD accounts, live-casino coverage and cryptocurrency deposit rails.

#88. Frank Casino

Frank Casino delivers a broad multi-provider slot library with distinctive brand identity. AUD-native cashier and standard offshore withdrawal windows.

#89. Joo Casino

Joo Casino runs a broad slot library with mid-tier welcome bonus and reliable AUD-native cashier. Multi-provider coverage including live-casino via Evolution.

#90. Genesis Casino AU

Genesis Casino's Australian-facing product uses a cosmic-themed brand identity with broad slot coverage. AUD accounts and standard offshore payment methods.

#91. Slotty Vegas AU

Slotty Vegas Australian-facing product delivers slot-first branding with SuperMax bonus mechanics. AUD-native cashier and broad multi-provider coverage.

#92. Voodoo Dreams Casino

Voodoo Dreams Casino uses a distinctive brand identity with broad multi-provider slot coverage. AUD-native cashier for the Australian market.

#93. Rizk Casino AU

Rizk Casino's Australian-facing product includes the Wheel of Rizk gamification layer alongside a broad multi-provider slot library. AUD accounts supported.

#94. Guts Casino AU

Guts Casino delivers a broad multi-provider slot library with Australian-facing product. AUD-native cashier and reliable offshore payment methods.

#95. Highroller.com Casino

Highroller.com Casino targets higher-stakes players with broad multi-provider slot coverage and strong live-casino integration via Evolution. AUD accounts supported.

#96. LSbet Casino

LSbet Casino pairs a sportsbook product with a casino offering, giving cross-vertical account structure for Australian players. AUD-native cashier.

#97. Boom Casino

Boom Casino delivers a broad multi-provider slot library with distinctive brand identity. AUD-native cashier and PayID rail support.

#98. Wazamba Casino

Wazamba Casino uses a jungle-themed brand identity with gamification retention layer on top of a broad multi-provider slot catalogue. AUD accounts.

#99. Playfina Casino

Playfina Casino runs a broad slot library with mid-tier welcome bonus and reliable AUD-native cashier. Cryptocurrency deposit rails alongside standard cards.

#100. LibraBet Casino

LibraBet Casino rounds out the top 100 with a broad multi-provider slot library, AUD-native cashier and standard offshore payment methods including PayID rail support.

Legal Framework for Australian Players

The Interactive Gambling Act 2001 (IGA) prohibits Australian companies from providing or advertising real-money online casino services to Australian residents. The law does not criminalise players who access offshore-licensed casinos. In practical terms, this means Australian players participate on offshore platforms with international regulatory oversight rather than domestic recourse. This is an important structural feature: offshore licensing (Curaçao, Anjouan, Malta) provides a regulatory framework but weaker player-recourse channels than domestic licensing would. Players are advised to verify each specific operator's licensing status and player reputation before depositing.

PayID and Australian Payment Rails

PayID is the dominant Australian payment rail for online casino play in 2026. PayID uses the New Payments Platform (NPP) to transfer funds using an email or phone number as the identifier, and PayID deposits credit within about 60 seconds at operators with the integration. POLi is a secondary Australian rail available at some operators for direct bank transfers. Credit and debit cards (Visa, Mastercard) are supported at most Australian-facing casinos but may face processing restrictions from some Australian banks that block gambling merchants. Cryptocurrency (Bitcoin, USDT, ETH) is widely supported at offshore casinos serving Australia and offers 24/7 processing outside banking hours.

Pokie Providers Available to Australian Players

The Australian offshore-licensed casino segment carries a broad and consistent set of pokie providers. Pragmatic Play dominates the mainstream slot category with Sweet Bonanza, Gates of Olympus and the Big Bass Bonanza series. NetEnt delivers the international classics — Starburst, Gonzo's Quest, Dead or Alive. Play'n GO covers the Book of Dead franchise and Reactoonz. Push Gaming's Razor Shark and Jammin' Jars are widely available at Australian-facing casinos following the studio's 2022 acquisition by Aristocrat Leisure. Nolimit City provides the extreme-volatility tier with Tombstone R.I.P. and San Quentin xWays. Aristocrat's own catalogue includes the classic Australian pub pokie titles — Buffalo, Queen of the Nile and Big Red — that resonate strongly with Australian players familiar with the physical machines.

Withdrawal Speed at Australian-Facing Casinos

Withdrawal speed varies substantially across the top 100 Australian-facing casinos. Golden Crown, LuckyVibe and VipLuck consistently clear verified withdrawals within 24 hours through PayID, which is the fastest fiat rail available. Cryptocurrency withdrawals process within minutes to hours at most operators regardless of the specific rank. Card and bank-transfer withdrawals typically take 1-3 business days depending on the issuing bank's schedule and the specific operator's internal processing window. First withdrawals take longer than repeat withdrawals because of the KYC review; subsequent withdrawals move through the internal queue without repeat verification. Minimum withdrawal amounts vary from A$20 at the most player-friendly operators to A$100 at more conservative operators.

Bonus Structures at Australian-Facing Casinos

Welcome bonus structures at Australian-facing offshore casinos in 2026 vary widely. Golden Crown, LuckyVibe and VipLuck run competitive matched-deposit welcome tiers at 100%-200% with wagering multipliers between 30x and 40x on bonus only. SkyCrown and Rooster.bet emphasise ongoing weekly promotions rather than large single-tier welcome bonuses. Cryptocurrency-focused operators in the top 100 typically offer a separate crypto welcome bonus with slightly different terms — often larger headline percentages but higher wagering. The 10x wagering cap that UKGC introduced for the UK market does not apply to offshore-licensed casinos serving Australia, so wagering multipliers at Australian-facing operators are higher on average than at UKGC-licensed operators.

Mobile Play at Australian-Facing Casinos

Mobile play at Australian-facing offshore casinos is delivered primarily through responsive web versions rather than native App Store apps, because Apple's App Store rules restrict real-money casino app distribution in jurisdictions without local licensing. Android APK downloads are common at the top 100 operators — the operator distributes the APK directly from the site, and players install it after granting a one-time permission to allow installations from unknown sources. iOS is served through Safari's Add-to-Home-Screen PWA flow: the mobile web site added to the home screen behaves as a full-screen application without the browser address bar. The mobile experience is functionally equivalent to native apps for most Australian players, and biometric login through Face ID or Touch ID is available through the browser session at operators that have integrated the WebAuthn standard.

Frequently Asked Questions