Givealittle's decision to start charging a 5 percent fee from September could put people off donating, says an organiser of the Awaroa beach fundraising campaign.
The crowdfunding website has not charged people anything to date, but it said it needed to now to ensure it could continue operating.
The amount raised on the website by individuals and groups has grown in the past three years from $500,000 a year, to $22 million a year.
Givealittle chief executive Tom Beyer said the fee would help ensure long-term stability.
"The growth and that generosity over the last three years has been quite phenomenal. It's now at 40 times the volume that it was four years ago.
"And that volume of generosity comes with costs and we pay a lot of money in bank fees, and payment processing fees and web posting cost as well.
"And we have an awesome team that looks at every page created on the site before it can take donations."
There were a total of 12 staff members working for the website.
Even with the fee, Givealittle would not make a profit, and the difference would be covered by the Spark Foundation, Mr Beyer said.
He did not know if the charge would put people off.
But Duane Major, one of the founders of the campaign to buy the Abel Tasman beach, said if a 5 per cent fee had been around then it may have been harder for the fundraisers to reach their goal.
"What you'd have to do is be transparent about it and say look we're aiming for $2 million ... and $100,000 [on top of that]. I suppose then, the choice then goes down to people who pledge - whether they'd be able to.
"I'd like to think we would have [reached our donation goal], but certainly it would've been another consideration."
He said the fee would be a barrier for those wanting to raise much smaller sums of money.
Jonathan Board had used the site half a dozen times to fundraise for charities and half-marathons.
He said he always managed to raise more money if he used Givealittle and he would still use the website even if there was a fee.
"You want as much of your money to go to charity as possible, but for the benefit of the charities as a whole, it's probably better to have the site running and to charge a small fee than to not have the site at all, because overall the money going to charities would be much less," Mr Board said.
Mr Beyer said people who donated to causes would also have the option to make a second donation - to contribute to reduce the 5 per cent fee.