The clicking of keyboards fills the hall at a former London dockyard hosting a 24-hour "hackathon" to design applications ranging from the whimsical to the practical and even the potentially life-saving.
The mood inside is studious and intense: over 200 competitors stare at screens, desks covered in cables, flash drives, soft drinks and sweets.
"We all have the ambition to make something unique and innovative," said Brian Thai, designing an app to allow victims of natural disasters to alert emergency services to their location with a text message.
"But I also recognise that innovations like WhatsApp, Facebook and Twitter... It doesn't come overnight. It's many years of generation," he said.
Fashion student Keit Kollo said she was creating a plexiglass prism to project hologram-like images.
"If you look at it from the right angle it seems as an actual 3D object... I hope we can build something very close to magical," Kollo said.
Her teammate Mansimran Singh sounded more sceptical, saying: "We just need to test it works because if it doesn't we have to come up with another idea."
The London leg of the "BattleHack" contest is one of 14 being held around the world this year, with the finalists selected for the final in Silicon Valley in November and a top prize of $100,000 (91,000 euros).
It was held on the same weekend as thousands of runners took part in the London Marathon.
Jon Havan and his team won the London contest in 2014 with a translation app.
"A day really isn't enough time to create something that would be, say, the next WhatsApp or Facebook but it does lead you down the path of something that could be along those lines," he said.
The contest at Tobacco Dock in east London is organised by PayPal, the US online payments giant.
John Lunn, one of the judges and a senior global director for Braintree, a branch of PayPal, said the idea was "to make something that makes you go 'wow'".
Contestants have to use Braintree or PayPal software.
"They can learn from our products and we can learn from them what works and what doesn't work," he said.
The contest is not so much about programming skills as brainwaves that could just be the next big thing.
During 24 gruelling hours, some of the contestants struggle to stay awake while others lie down on sofas.
A gong is sounded to signal the end of the challenge and the programmers give presentations of their inventions in front of a panel of experts.
The winner is an app that sends out an alert if it registers a break in the daily usage of electronic equipment by elderly people living on their own, for example by monitoring when the television is on.
"It's a good validation of our idea and publicity," said Sam Machin, co-creator of the project.
"There's probably something in it," he added.
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