A Covid-19 contact tracing app developer says the Government's app could do more harm than good.

Steve Nathan created Time Hub, which private businesses and golf courses are using to keep track of their customers.

Nathan claims many people will not use the government app, and could make it harder for businesses to enforce their own tracing measures.

"If I walk into a shop and I don't have the app, does the shop then have to stop me, ask me to fill in a piece of paper, use their other app? The one thing we can't have at the moment is complacency."

Nathan adds the Government app could make it harder for businesses to enforce their own measures, and may not have a high take up itself.

He says people cannot, will not or cannot be bothered sing the app, there will not be any data to collect.

The app was made available to the public overnight.

The Government's contract-tracing app has been released. (Photo / Herald)