Webstock organisers say they will be reviewing the vetting of their speakers and thanked people for their empathy after a controversy on Friday.

Organisers of Wellington's Webstock technology conference have issued an apology after an invited speaker struck a bum note by embarrassing the event's sign language interpreter.

New York graphic designer Stefan Sagmeister attempted humour with a skit that involved having the interpreter, Jennifer Gilbert, repeatedly sign the translation for "blow job".

Sagmeister tweeted an apology after a fierce backlash from conference goers and a furore on social media.

I made a joke that was highly offensive. It was wrong & I'm deeply sorry. I sincerely apologize to NZSL interpreter, Jenn Glibert. - Stefan — Sagmeister & Walsh (@sagmeisterwalsh) February 18, 2017

Gilbert brushed off the incident in a tweet as a "tiny blip". She later tweeted she had accepted the apology from Sagmiester, whose speaker's fee would be donated to the Sign Language Interpreters Association.

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Conference organiser Natasha Lampard said in a statement on Sunday that Sagmiester's behaviour was wholly unacceptable.

"We did not ask Stefan to stop speaking. We will debate whether that decision was the correct one for a long time to come," she said.

A statement from the Webstock team https://t.co/Gg5gESuiXd — webstock (@webstock) February 19, 2017

Sagmeister has been in contact with me and apologised, I have accepted his apology. His speakers fee is being donated to @SLIANZ#webstock — Jenn Gilbert (@posyjenn) February 19, 2017

Sagmeister's speaking slot had been rejigged after another keynote speaker at Webstock was unable to deliver her address at the allotted time after she was hit by a car in the central city.

Patricia Moore was due to close the conference, recounting how in the 1970s, she spent three years travelling around the United States disguised as an 80 year-old to see how that changed the way she was treated as a consumer.

But she instead addressed the conference a day early from hospital.

It is understood she was hit by an elderly driver.

Moore was recuperating on Friday and has not been available for comment.

Webstock is now in its 12th year, and continues to attract top tech industry personalities from around the world, attracted by its broad and sometimes quirky agenda.

Cal Henderson, co-founder and chief technology officer of rapidly-growing messaging and online collaboration firm Slack spoke at the conference, nine years after he first attended as a co-founder of photo-sharing site Flickr.

Commenting before Sagmeister's address, Henderson said it was "the best tech conference in the world".

"The conference organisers are amazing. New Zealanders are so nice and it has an amazing vibe."

The praise is high coming from Slack, which was last year valued at US$5 billion by venture capitalists and was described by Forbes as the fastest-growing workplace software company ever.

Slack has brought communication tools that used to largely in the domain of software developers to a much broader market, but faces fresh competition this year from Microsoft Teams, a similarly-positioned service.

But Henderson said the competition would grow the product category by helping people realise there were alternatives to existing communications tools.

"One of the big problems with email is your open up your inbox and it is mails from your colleagues, mail from your family, and automated notifications from the likes of Facebook and Twitter – everything all in one big mess."

One of Slack's goals this year was to apply machine learning to help people discover what was most important in the communication channels they subscribed to in Slack, Henderson said.

"Knowledge workers spend about 20 per cent of their time looking for information and if we can cut that down just a little, that is going to be huge."