Twitter co-founder Jack Dorsey has officially launched his new company, called Square, that sells a system to turn mobile phones into payment card readers.
Square, which Dorsey officially announced to the world with a tweet, sells a piece of plastic that fits in to the headphone jack of a phone.
The customer swipes their card in the device and confirms by 'writing' their signature with their finger before a receipt is sent to their e-mail address or mobile phone instantly. Customers can also use a text message to authorise payments in real-time.
Users can create a Square payer account to speed up and secure payments and upload a photo so merchants can verify the card holder.
On its Web site, the firm boasts merchants can get from "0 to $60 in under 10 seconds" with no contracts, monthly fees, or hidden costs. It will also donate a penny of every transaction taken by merchants to a cause of their choice.
The company has been touted as the real world equivalent of PayPal and, according to TechCrunch, is already valued at $40 million after raising $10 million in a funding round.
Dorsey explains and demonstrates the system in a video for TechCrunch here.