Bank Provide API: Direct bank API vs BaaS vendor integration

The question in full

A 2026 technical guide for fintechs determining their integration path. The article explores whether a Licensed Financial Institution (LFI) provides a native API or if they rely on a Middleware Vendor for tech support and connectivity. It details the "Direct-to-Core" development model, the role of RESTful APIs in modern banking, and the importance of Sandbox Environments for backend testing. Key themes include the ISO 20022 messaging standard, OAuth 2.0 security protocols, and how to distinguish between a bank's "Marketing API" and its Transactional API.

Answer

The licensed financial institution does indeed provide an API stack that you would be working and integrating with. In most cases, your billing will start the moment your API goes live. Some institutions have a sandbox environment that allows for ‘most’ of the development to happen without going live and some do not have a sandbox environment at all. It all depends on one solution provider to another.

Regarding the API we have a vendor that helps with Tech Support. We will work with the bank directly to develop our back end. Does the licensed financial institution provide an API?

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