Health Minister Stephen Donnelly has appealed to people to download the new Covid-19 Tracker app.
The app has been downloaded by more than 200,000 people since it became available on Monday night.
Minister Donnelly said "today is a good news day" for the country's fight against Covid-19 with the launch of the app.
"Please download this app."
Health Minister Stephen Donnelly says he understands concerns from the public about data privacy, regarding the Covid-19 tracker app.
He said: "Those concerns are very real and reasonable. The app has been developed with privacy by design at its core. We are also encouraging friends and families to help those that may not be as technically literate, to download and use the app."
"We've ensured that from the very first version, the app is available in English and in Irish, and we are very much open to incorporating other languages in future upgrades as we receive feedback."
HSE chief executive Paul Reid confirmed the Covid-19 tracker app has been downloaded by 250,000 people since it was launched on Monday night.
Mr Reid said he "had a dream that we had a quarter of a million users of this app".
"I can confirm that it isn't a dream, we have that many users. It is a phenomenal achievement."
HSE chief executive Paul Reid said there is no target for the number of people to download the Covid-19 tracker app.
He said: "If every one of us asks all of our network to download the app today, we will capture everyone we need... If everyone asks everyone in their network to download this app - that's the level we're looking for in uptake."
He added the app is not a "silver bullet" and said the app will compliment the existing contact tracing system.
Acting chief medical officer Ronan Glynn said until there is a vaccine against Covid-19, social distancing, hand-hygiene and mask-wearing will be key to battling the virus.
"The Covid-19 tracker app will be a very important addition to this."
Dr Glynn says the app will "increase our capacity to combat the spread of the disease".
"We realise that high uptake requires public trust and confidence... This is why such attention has been paid to data protection and privacy"
Dr Glynn said research shows that a large majority of the Irish public said they would download the app and he is confident people will get on board with it.
Health Minister Stephen Donnelly said the Covid-19 tracker app is "effectively all-island".
He said the app does not differentiate where it is on the island of Ireland and it will work everywhere, regardless of internet access or coverage.
"The app works with bluetooth technology - it works phone-to-phone. If two people meet on top or Carrauntoohil for 15 minutes - the phones will log that."