If you're talking about European banks they all have APIs. But only licensed companies can use them directly. Those companies are called AISPs within the PSD2 framework, sometimes referred to as aggregators. Some of them have ways for individuals to access their own accounts at banks via the AISP APIs. But there are limitations, one major one being that PSD2 doesn't cover credit card data or anything other than deposit accounts. [I'm a product manager at a bank]