At the end of the day, the cards are scanned again to "clock" out the workers.

Capps' founder Sean Chew said: "This system enhances productivity. No more paper and pen. The information is sent via the phone to the employer's office where it is automatically tallied against workers' overtime and salaries.

"It saves a lot of time and paper work for the companies."

The software, called PayAdvisorMobile, is a real-time attendance and salary management system, integrated with payroll functions, said Mr Chew.

It is aimed at firms with moving worksites.

Mr Chew said it was not viable for his company to develop customised solutions for small and medium-sized companies.

The cost of producing each solution, at between $40,000 and $80,000, was too expensive.

A software product made more sense as it is developed once, and can be sold to many companies.

"With the manual system, there can be arguments over the actual times workers 'clocked' in. Once we've automated it, there're no more arguments over timing inaccuracies.

"There are many permutations to workers' overtime pay. For example, (someone) who works over a certain amount of hours is paid more in overtime. These used to be computed manually, which led to mistakes."

The app also lets employers automatically record the number of days worked, as well as medical leave taken.

Mr Chew said his product is generic and can be used by any company in the construction or logistics industry.

To start using PayAdvisorMobile, employers must download the free app and sign up for the service, which costs about $4 per worker a month.

The app is available for Apple and Android-based mobile devices.