Twitter chief executive Jack Dorsey has sold a digital version of his first tweet for more than $US2.9 million ($A3.8 million) more than two weeks after he announced a digital auction for the post.

The tweet from March 2006, which says “just setting up my twttr,” was bought by Bridge Oracle chief executive Sina Estavi, according to Valuables by Cent, the digital platform where the digital auction for the tweet was held.

The 15-year-old post was sold as a non-fungible token, or NFT – a digital certificate of authenticity that confirms an item is real and one of a kind by recording the details on a blockchain digital ledger.

Mr Dorsey tweeted earlier in March that the proceeds would be converted to bitcoin and given to the non-profit GiveDirectly’s Africa Response.

The charity has been raising money to support African families who were financially impacted by the coronavirus pandemic.

A screengrab from the bidding war for Jack Dorsey’s first tweet. Photo: AAP

According to Valuables, 95 per cent of of the proceeds from the sale price go to the tweet’s creator and 5 per cent of it goes to the platform.

Mr Dorsey tweeted the bitcoin receipt on Monday afternoon and said the funds were sent to the charity.

NFTs have recently swept the online collecting world. A digital artwork by the artist Beeple sold for $US69.4 million ($A58.2 million) in an online auction by a British auction house earlier in March, with an NFT as a guarantee of its authenticity.