Westpac Banking Corp has moved to counter Square’s momentum in the small business payment device market, updating its fleet and turning to open-source software that will allow it to create credit products at the point of sale.

Westpac will issue 100,000 lightweight, mobile “Eftpos Now” terminals to SMEs, four months after Commonwealth Bank announced a similar upgrade to its ageing Albert fleet, as Square’s devices and accompanying sales software rise in popularity.