So You Want To Develop A Fintech App: Financial API Integration

 In Apps, Data, Developers, Financial APIs, Financial Data, Open Banking, Portability

In 2021 there were over 573 million downloads of mobile finance apps in the United States alone. According to Google research, the average smartphone user has three fintech apps on their phones, and 4 in 10 people use them regularly for various financial activities. Spurred by the COVID-19 pandemic, fintech has grown exponentially in recent years, and it seems like there’s no going back to the way things were before. Fintech apps open up many beneficial possibilities for users to manage their personal finances, engage in investing, pay bills, and so much more.

In order for any fintech app to work, it has to have access to users’ financial information coming directly from their financial institution. Enter: financial data APIs. Financial APIs (otherwise known as bank APIs) are the pathways between the app you’re developing and your users’ bank accounts. Once the APIs are established, they facilitate the ongoing, instantaneous, and secure porting of user financial data to your app.
In this article we’ll discuss the process of integrating financial APIs to the fintech app you’re developing.

What Are APIs?

API stands for “application program interface,” and it refers to the mode by which two separate computer programs communicate with each other. APIs are like the highways connecting entities that would otherwise be isolated from each other. For our purposes in this series, we’ll be discussing a specific branch of APIs known as Web APIs. Within Web APIs there are three main subcategories: internal, partner, and open.
1. Internal, or private, APIs connect two or more structures within one company and are not intended to be accessed by any third parties.
2. Partner APIs build connections between two companies’ systems but have limited authorization, and are only used between formal relationships between organizations.
3. Open APIs (also known as public or external APIs) are available to any developer and make it possible for various kinds of data to be shared openly with many third-party organizations.

Camwilliams96, CC BY-SA 4.0 via Wikimedia Commons

Let’s look more specifically at the integration of open financial web APIs into your fintech app.

Bank APIs for Developers: How to Integrate

Establishing APIs is one of the most important steps of building your fintech app since, like we said before, your app can’t do what it’s meant to do without these ongoing connections with financial institutions. As a developer, the best option you have is to use open banking APIs because they allow you to reach as many potential users as possible. With open APIs, your app will be able to receive data from essentially any financial institution your users bank with instead of limited ones. Simply by choosing open APIs with the right provider, you make your app relevant for anyone who uses any kind of banking services, whether the institution is a traditional bank, neobank, online bank, or anything else.

It is possible to develop your own open APIs to use with your app, but we don’t recommend that since it would take a really long time. The better option is to employ a technology platform that already has open financial APIs and aggregates financial data for third-party apps like yours. There are a lot of different options for API platforms, so we recommend looking for some specific things when considering any one of them.


First of all, usually API platforms provide some kind of tutorial or guided simulation of what it’s like to use their services. If they have it, then you should be able to find it quickly by searching their website for a “Quick Start” page or a “Tutorials” section on the site. The tutorial ideally is quick and easy to experience, without requiring any software installations or configurations. It should also be as true as possible to the actual integration process if you choose to use this platform.

An example of part of a tutorial for financial API integration

The key benefit of working through Quick Start examples, or tutorials, is to get a feeling of how difficult the integration would be for your case. On top of that, you can get a sense of how good the API is from a product point of view: usually great technology platforms are also great at making things look easy.

An additional benefit of working through a tutorial for an open banking API is that you may immediately find how to use the API for your use-case, whether it’s a cashback app, a finance management app, or some other kind of application. If you don’t see your use-case mentioned at all, however, or cannot visualize how to utilize a certain platforms API to make your own app work, that may be a red flag.

A good open banking tutorial for a financial API should be sufficiently clear and easy enough to reproduce that a product manager – not just developers – should be able to reproduce it in minutes and understand if it’s accurate or not (on this note, we think that our own tutorial is great! You can check it out here). If the tutorial makes you spend two hours in installation and configuration, that’s a bad sign: open banking APIs aren’t the simplest systems on earth, but from a user perspective they should be straightforward.

Documentation and Credentials

If you like the tutorial experience from a specific platform, next you’ll probably want to look more deeply at their documentation and credentials. Spend some time on their website to learn more about who they are as a company and who their founders and engineers are, if you can. As you consider working with this platform, you also want to consider what the interface of working with them is like. Also, what services can they provide to you in addition to simply establishing financial APIs? What kind of data do you need, and can they put it together for you in a way you like? For example, do they offer methods for analyzing financial API data?

For any financial data provider, it should be pretty easy to find the documentation site of their APIs. Once you have that, give it to one of your engineers for their review.

The point of all of this is to make a judgment call on how good a specific platform’s system seems. That may sound vague and subjective, but it’s actually based on the experience of you the developer. Here are some other questions to ask as you get a feel for a specific API provider:
Do they follow standards and best-practices?
Do their services look both comprehensive and easy to digest? (yes, that’s possible!)
Does it seem as if it was written by a developer?
One of the worst mistakes you can make is to judge documentation from a purely aesthetic point of view, when in reality it’s just a site made up by a professional designer and doesn’t communicate software development concepts well. Keep this in mind as you continue to peruse a specific site or interact with a potential provider.

An example of part of a platform’s privacy policy page

Other Check Boxes

A few other things to consider: it’s important to find a platform with the widest possible coverage so that your app has the greatest possible reach. In addition, you’ll want to consider the security protocols the platform follows in establishing and maintaining their APIs. You only want to integrate with a platform that abides by standardized processes that are approved by the actual financial institutions your future users bank with.


Testing and APIs

In the first article of this series, we touched on the crucial step of testing your fintech app before launching it. Testing the APIs is an important aspect of that step. To do that, you’ll need to have a robust payment transaction dataset to practice running through your app. If you choose the right platform for your APIs, they should be able to offer real, consumer-permissioned datasets for you to test with because of their existing APIs. Like we said before, having real live data is by far the best option for thorough testing to ensure your app will work for every user before it goes live. We’ll discuss this step more thoroughly in our next blog post, coming soon.

Integrating Financial APIs with Pentadata

Pentadata is the first financial data platform in North America that uses encrypted, consumer-permissioned APIs to access data from virtually all leading banks, payment processors, payment networks, and data platforms while also adhering to stringent technical standards and best practices aligned with the twelve major North American financial institutions. We always require consumers’ permission before their data is accessed, and we never store consumer data that’s being ported to your app, which makes it vulnerable to being accessed by the wrong people. If you choose to work with us to build your app, we have unique analytical tools that can provide you with the insight needed to take meaningful action.

Maybe the best news is, while most portability platforms can give you access to financial data within a week of it being requested and permissioned, Pentadata can grant access typically within 24 hours of consent being given by the user so you can be up and running in no time. When time is of the essence, we have what you need to safely and securely get your app not only ready to launch but also continuously onboard new users.

If you want to explore how to integrate Pentadata’s financial APIs into your app, contact us to request API keys and try it out today!

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