Collaboration between fintechs and big banks is a hot topic on the conference circuit but a couple of bankers issued a reality check yesterday, saying collaboration was difficult to achieve for a whole lot of reasons.ANZ general manager deposits and payments, Katherine Bray, said the bank had done some collaborative projects that had worked out but there were many more where the parties had "walked away".Bray, who was speaking at the Australian Financial Review's Banking and Wealth Summit yesterday, said: "We no longer say we must do everything ourselves. We have got to get in there and play."But integration is hard. Those companies are very different from us."Another speaker at the conference, Westpac head of transactional solutions Mike Baldwin, said: "At Westpac we are investing in venture capital and we are supporter of Stone & Chalk. We talk to start-ups."That hurdle has been overcome but we also have to think about the stability of our core system."Westpac has been working with Ripple Labs and IBM to develop a low cost remittance system using blockchain technology. The project has reached the proof of concept stage, with staff trialling it by sending payments to New Zealand and Fiji.Baldwin said the bank had a product under development but integration into the banking system was proving expensive and it was "taking way too long".Baldwin and Bray said their banks saw opportunity in adopting an "open API" approach - that is, opening up their application programming interfaces to external developers.However, neither bank has made much progress. "The intent is there but we see that as something for the future. We are behind," Bray said.One company that has made progress with open API is Visa, which announced in February that it was opening up its payments technology to the developer community in a move aimed at allowing banks, retailers and technology companies to develop applications more quickly.Visa launched Visa Developer, which provides access to some of the company's technologies and services, including its account holder identification system, person-to-person payment capabilities, secure services such as Visa Checkout, currency conversion and transaction alerts.Visa Australia group country manager Stephen Karpin said one development that has resulted from the initiative was a collaboration between Visa, the car maker Honda and developer ParkWhiz, which has an app to help drivers find parking spaces and then processes the parking payment.The project involves putting an app in a car that sends a fuel alert to the driver and arranges payment at the bowser.