SINGAPORE - Developers around the world can now access the building blocks of Singapore's contact tracing app TraceTogether for free and make their own version to turn the tide against Covid-19.

The app's code is now officially open-sourced.

This news comes as the world's number of coronavirus-linked deaths inches closer towards the 100,000 mark, currently at about 95,000. More than 1.5 million people have been infected.

In a Facebook post on Thursday (April 9) night, Minister-in-Charge of the Smart Nation initiative Vivian Balakrishnan said that developers can find out more about TraceTogether's source code, the BlueTrace protocol, on tech.gov.sg.

"The BlueTrace protocol - on which TraceTogether is built - is designed to be interoperable, and the international community can develop and adapt it to their contact tracing needs," said Dr Balakrishnan, who is also Foreign Minister.

"We hope to work with other countries and public health organisations to enhance the codebase and BlueTrace protocol. It is important that we stand together as one in the global fight against this Covid-19 pandemic."

In a blog post on its website, the Government Technology Agency (GovTech), which developed the app together with the Ministry of Health (MOH), said on Thursday that more than a million users, or about one in five people here, have downloaded TraceTogether.

This still, however, falls short of the optimum number of users that is needed for the app to work well. In an interview with The Straits Times on April 1, National Development Minister Lawrence Wong said that in order for TraceTogether to be effective, Singapore needs about three-quarters of the population to have it.

In his post on Thursday Dr Balakrishnan urged more to download the app and use it.

Launched on March 20, the app can identify people who have been within 2m of coronavirus patients for at least 30 minutes, using wireless Bluetooth technology.

Its developers say the app is useful when those infected cannot recall whom they had been in close proximity with for an extended duration.

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For the app to start tracing, the Bluetooth setting on mobile phones has to be turned on.

If a user gets infected, the authorities will be able to quickly identify other users he has been in close contact with, allowing for easier identification of potential cases and helping curb the spread of the virus.

Official contact tracers will provide a code that users can match with a corresponding verification code on their app.

Once authenticated, users will get a PIN that allows data to be submitted.

Contact tracers will not ask for any personal financial details or request that money be transferred over the phone, said GovTech on TraceTogether's website, addressing concerns about potential phone scammers pretending to be contact tracers.

In his post on Thursday, Dr Balakrishnan said that the GovTech team worked over the last two weeks to make TraceTogether open-sourced.

ST understands that parties in Chile, the United States and New Zealand are interested in making their own versions of the app.

But MOH director of Analytics and Information Management Sutowo Wong stressed in GovTech's blog post that TraceTogether does not replace the contact tracing process.

Besides the app, Singapore also has physical contact tracing teams to track people who have been exposed to confirmed coronavirus cases.

"Instead, it is an important tool in the toolbox of contact tracers. It is not sufficient to rely on technology alone, as we need the expertise in public health and communicable diseases to make sense of the data collected using this technology."