Typeform said it had identified the breach on 27 June, with the data having been accessed from a partial backup of 3 May.
British digital bank Monzo was also hit by the breach, saying that the personal data of about 20,000 customers was likely to have leaked.
The TEC said Typeform online forms had been used on its website since 2015 for some of its election services.
The TEC said the breach had no connection to the national or state electoral roll.
Typeform said subscription payment information was safe and secure (credit card, address, etc), as also Typeform passwords. Any data collected since 3 May was safe. But the company did not give any indication of how the breach had occurred.
"If you collected payments via our Stripe integration, all of your audience’s payment details are safe," the company added.
Monzo said a total of 19,213 email addresses of its customers had leaked, as also postcode and name of old bank (1600); Twitter username and email address (1434); email address and university attended (908); name, email address, city, age band and salary band (191); name, email address and employer (53); and name and email address (7).
The digital bank was in the news recently, when it spotted potential signs of a breach at the American multinational ticket sales and distribution company Ticketmaster.