TransferWiseambitions of being a platform in the truest sense. In addition to its direct-to-consumer app, the company offers an API for integration with other fintechs and banks, although it is fair to say that third-party integrations of this kind have been quite slow to come by. With that said, the number of third-party integrations appears to be picking up pace.

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The latest bank to offer TransferWise  functionality is Dutch challenger Bunq, which is enabling customers to make “fast, low-cost international payments” powered by TransferWise. Similar to other third-party integrations, the TransferWise feature sits within Bunq’s own app, giving users the “real exchange rate”, in addition to a small, transparent fee. At launch, 15 currencies are supported, and over the coming weeks more currencies will be added.

Back in June when TransferWise unveiled its partnership with fast-growing U.K. challenger bank Monzo, I asked co-founder and CEO Kristo Käärmann how different the conversation is with the challenger banks compared to longer established incumbents who historically have made a lot of revenue from foreign exchange fees. Perhaps being diplomatic, he argued that those conversations are quite similar, and usually centres on the fact that customers are already using TransferWise and that if a bank wants to put those customers first it makes sense to offer TransferWise functionality within its own app.

“When we announced the large French bank [BPCE Groupe], which is clearly an incumbent — a massive incumbent — they were thinking about their customer,” he told me at the time. “That maybe does feel a little bit rare for banks to think this way, but they figured that ‘if we are going to do this, then why don’t we do it properly’. They were actually fully driven by their users and thinking about how to get the best user experience”.

Cue a statement from Bunq founder and CEO Ali Nikna: “Our mission is to free our users from borders and barriers in traditional banking, such as hidden fees. We think TransferWise is a valuable addition to solidify that mission. This is the next big step in bringing freedom to the traditional banking industry”.

Meanwhile, the Bunq tie-in is TransferWise’s fifth bank partnership. In addition to Monzo, and upcoming integration with France’s BPCE, the international money transfer service has partnered with Germany’s N26, and Estonia’s LHV. However, a previously announced partnership with the U.K.’s Starling Bank never materialised and has since been disbanded.