Determining the most popular free online slots can be subjective and may vary depending on factors such as player preferences, game features, and the region. However, some slots consistently rank high in popularity due to their engaging gameplay, enticing themes, and bonus features. Here are a few that are often considered among the most popular:

Starburst – Developed by NetEnt, Starburst is known for its vibrant colors, arcade-style gameplay, and expanding wilds feature. For more information please visit toto slot

Book of Ra – A Novomatic classic, Book of Ra takes players on an Egyptian adventure with free spins and a special expanding symbol.

Mega Moolah – This progressive jackpot slot from Microgaming offers the chance to win massive prizes with its four-tiered jackpot system.

Gonzo’s Quest – Another hit from NetEnt, Gonzo’s Quest features an innovative avalanche reels mechanism and a free falls bonus round with increasing multipliers.

Cleopatra – Based on the ancient Egyptian queen, Cleopatra by IGT is beloved for its simple gameplay, free spins feature, and iconic theme.

Buffalo – Developed by Aristocrat, Buffalo is a popular choice among players for its stacked symbols, free spins, and 1024 ways to win.

Bonanza Megaways – Created by Big Time Gaming, Bonanza Megaways offers a dynamic gameplay experience with its cascading reels and up to 117,649 ways to win.

Age of the Gods – Playtech’s Age of the Gods series comprises multiple slots with a shared progressive jackpot, featuring Greek mythology themes and various bonus rounds.

Immortal Romance – This vampire-themed slot from Microgaming boasts a captivating storyline, four unique free spins features, and a Chamber of Spins bonus round.

Wheel of Fortune – Based on the popular TV game show, Wheel of Fortune slots come in various iterations from different developers and typically feature bonus wheels and free spins.

Remember that popularity can fluctuate over time and can differ based on individual player experiences and preferences. Additionally, availability may vary depending on the online casino or gaming platform.