Some of the world’s biggest websites and apps — including Snapchat, Reddit, Telstra, Optus and Microsoft Outlook — have been hit by a global outage stemming from Amazon’s cloud services.

Businesses were disrupted globally in the largest internet disruption since last year’s CrowdStrike malfunction hobbled tech systems in hospitals, banks and airports.

The latest problem, which affected thousands of websites, was triggered by a simple IT glitch at Amazon’s cloud services unit AWS.

The ensuing meltdown highlighted the vulnerability of only a few services, like Amazon, accounting for most of the world’s interconnected technologies.

AWS competes with Google and Microsoft’s cloud services.

Ookla, owner of outage tracking website Downdetector, said more than 4 million users reported issues due to the incident.

Some affected services included Telstra, Optus, 9Now, Snapchat, Fortnite, Canva, Tinder, Duolingo, Strava, Disney+, Lloyds Bank, Slack, Life360, BT (British Telecom), Bank of Scotland, Vodafone, Whatsapp.

After roughly three hours of disruptions, systems were gradually coming back online late Monday and early Tuesday (AEDT). AWS said it was seeing “significant signs of recovery” for some affected services.

“Most requests should now be succeeding. We continue to work through a backlog of queued requests,” it said in the latest update posted on its status page.

AWS provides on-demand computing power, data storage and other digital services to companies, governments and individuals.

Disruptions to its servers can cause outages across websites and platforms that rely on its cloud infrastructure.

Amazon did not respond to a request for comment.

Junade Ali, a software engineer, cyber expert and fellow at the Institution of Engineering and Technology, said the issue appeared to be with a networking system AWS uses to control a database product.

“As this issue can usually be resolved centrally … unless there are further issues identified, the issue should be able to be mitigated over the coming hours,” he said.

Issues on some apps and websites, including Snapchat, Roblox, streaming site Max and PayPal’s Venmo, were showing signs of easing, according to Downdetector.

Snapchat last had more than 4000 reports on Downdetector, down from an earlier peak of more than 22,000. Reports on Roblox dropped to less than 500 from a peak of more than 12,600.

Other services, however, remained affected. There were thousands of reports for social media app Reddit and financial platform Chime on Downdetector.

AI startup Perplexity, cryptocurrency exchange Coinbase and trading app Robinhood all had platform disruptions that they blamed on AWS.

Amazon’s own services, including its shopping website, Prime Video and Alexa, were also hit although Downdetector last showed a decrease in severity.

Fortnite, owned by Epic Games, along with Clash Royale and Clash of Clans, were among the gaming platforms affected.

Uber rival Lyft was also knocked down in the United States.

In a post on X, Signal’s president Meredith Whittaker confirmed the messaging app was hit by the outage as well, although billionaire Elon Musk, who owns X, said his platform continued to work.

In Britain, Lloyd Bank, Bank of Scotland and telecom service providers Vodafone and BT also had issues, according to Downdetector’s UK website, as was UK tax, payments and customs authority HMRC’s website.

The problem highlights how interconnected everyday digital services have become and how reliant they are on a handful of global cloud providers, with one glitch causing havoc with business and day-to-day life, experts and academics said.

“The main reason for this issue is that all these big companies have relied on just one service,” said Nishanth Sastry, Director of Research at the University of Surrey’s Department of Computer Science.

AWS competes with Google’s and Microsoft’s cloud services.

-with AAP