Organisers "absolutely" feared the Hay Festival might not go ahead due to coronavirus, its director has said.
The 33rd edition of the literary event, usually held in Powys, will be free and broadcast online from Monday to 31 May.
Donations totalling £350,000 have helped it go ahead in this digital format.
Director Peter Florence said: "It looked alarming, but festival-goers are generous and imaginative in their response to crisis."
He said the announcement of lockdown on 23 March came at a moment of "maximum exposure" for Hay's organisers, who had just committed to £1m of spending for the event.
"It was an existential crisis for about a month. And we were absolutely blown away by the response of our audiences and our sponsors," he said.
"We had to claw back - we were starting from a ropey position.
"We found untapped reserves of creativity and invention in the organisation, so it's been pretty encouraging."
Hay-on-Wye would normally have been welcoming hundreds of thousands of visitors to the internationally-renowned festival this month.
And with 70% of the festival's income usually coming from ticket sales, the impact of the pandemic on the event is stark.
Mr Florence said it had forced the organisers to "trim down massively" - cutting the operation to about a third of its normal size and putting 50% of the workforce on furlough.
However, he said the "major impact" was on the local area, which had suffered a "profound shock to the system" by the cancellation of the event proper.
Traders in the market town have said it will be a "massive blow".
The festival brings an economic boost of about £28m every year to an area made up mostly of smaller, independent businesses and traders.
"That's what we wanted to stay alive to protect and to give some sense of future for," Mr Florence added.
But despite the "big turnaround" of having to effectively shift from being an event company to a broadcaster, Mr Florence said it had been "exhilarating".
This year's programme is no less star-studded than usual, with Benedict Cumberbatch, Helena Bonham Carter and Margaret Atwood all set to appear.
Writers, policy makers, historians and activists will take part live from their homes and will answer questions from viewers.
There will be a series of broadcasts for schoolchildren between 18 and 22 May, featuring Children's Laureate and author Cressida Cowell.
Authors Hilary Mantel, Roddy Doyle, Ali Smith and Sandi Toksvig will be among the writers previewing their new work.
And Mr Florence highlighted the "most-extraordinary cast" set to celebrate the life of William Wordsworth, including festival president Stephen Fry, Tom Hollander and and Jonathan Pryce.
He said the digital festival had clearly struck a chord; Hay usually sells about 275,000 tickets and there have been more than 200,000 digital registrations for this year's event so far.
Across Wales, Covid-19 has put paid to numerous live events, with the Welsh Government calculating the direct economic impact on those it supports at about £33m.
That may mean digital alternatives will be here to stay for some time, Mr Florence said.
"The model that we used to have, of flying in writers and thinkers and artists around the world, that's that's not going to come back anytime soon," he added.
"And we as producers, the artists as creators, and the audience as participants, will all adapt to whatever new reality is possible."
That said, Hay's organisers remain optimistic the full festival will run in 2021, with this year's event acting as a gateway for visitors to enjoy the "social closeness" fundamental to the Hay experience.
"It will be thrilling if people get a taste for the full bells and whistles, tents and delights that take place in a field in Wales," Mr Florence said.
"Because there is nothing that replicates human touch and being together."