The Companies Office register, along with several other transactional Ministry of Business, Innovation and Employment websites, is back after being offline since at least 2.30pm yesterday.
The site, which had been unavailable for company and director searches, was working again by about 11am.
A ministry spokesman said there had been "performance issues" which meant the ministry had to disable the transactional parts of its websites.
The Companies Office - through the also-disabled iGovt identification system - has credit card details for information purchases.
That includes the Personal Properties Securities Register, the Intellectual Property Office register the companies register and the Financial Service Providers Register.
Although the website landing pages worked normally, attempts to search the registers reverted to a temporary outage message.
The National Business Review reported a reader had seen the message "Hello World" displayed just after the site went down, but the ministry said that was not suspicious and a default message.
- The Press