How Consistency and Collaboration Lead to API Success at Fiserv

Fiserv’s mission was to simplify the entire payment journey model into a single API call. They used Stoplight Platform to create consistency.

Focusing on merchant acquiring, Fiserv enables businesses to accept payments online or in store, leveraging their suite of APIs and point of sale terminals. APIs are important for fulfilling the entire payment lifecycle, from taking that initial payment from a cardholder, to a business receiving the money in their bank account - and not to forget all the actions that happen behind the scenes to enable that experience.


Their goal is to give merchants a full, connected picture of how their business is performing on the payment side, which is the most important part of Fiserv’s offerings. Merchants use Fiserv to make sure they can sell their products most efficiently and ensure that they have the transactional technology and data that they need to optimize their business.

In addition to meeting their customers’ needs, Fiserv wanted to establish internal outcomes:

Establish API program maturity
Create an API-first culture
Embed API design in the business
Easily lift from internal APIs to external
Quality improvements
Increased innovation, engagement, and conversation


If you dive into the full payment journey you’ll discover that so much happens in the backend like authorizing transactions, connecting to different card brands, settling transactions, and providing many other ancillary services.

Part of Fiserv’s mission - and one of their biggest challenges - is to simplify as much of that journey as possible for both the cardholder and the merchant. Clients shouldn't have to worry about all the ins and outs of what Fiserv does to facilitate a payment.

Simplifying all of the payment journey model into a single API call and making sure that it works as efficiently as possible is the ultimate challenge. Fiserv has been developing their technology for years, and clients currently depend on the service.

However, another challenge has been making clients understand how the payment journey works.


Fiserv has since established an API program tailored to meet the needs of customers and their own business. The API program team is composed of API Product leaders focused on scaling the solutions the company offers to partners and merchants. The team followed these tactics in order to scale their program.

Establish an API Framework through Design-First

The company first established its API framework by analyzing the different APIs used by merchants, enterprise customers, and other payment landscapes.

Connect with Developers through a new Developer Portal

As more companies become aware of APIs. Fiserv has seized the opportunity to develop a set of consistent APIs. The new Fiserv developer portal provides an ideal space where developers can experience documentation and APIs themselves.

Create Consistency

Consistency in this context means the entire development team feels part of the project even if different project managers have developed the different components of the APIs. Different APIs come with different sets of data and headers; how data gets queried can be confusing and difficult to consume. Initially, developers had to write many cases and codes to enable different operations for different APIs. This tedious process is not ideal for the API program; therefore, consistency is achieved by having the APIs have a single voice and adhere to a style guide.

From a customer’s perspective, a developer defines consistency as seeing the company as one unified entity. But in reality, the process involves many different teams who create the whole product. The massive amount of data and payments involved mean different teams are working on different components to develop the final product, but the goal is to give all customers a consistent, predictable, and secure experience.

Tools and processes

Different tools and methodologies are required to ensure that the team can provide reliability and consistency across the different APIs. The company relies on its API product designers and managers who create and work with the different domains and business areas to help in understanding the customer’s perspective.

"Because APIs simplify how developers integrate new application components into an existing architecture, they help business and IT teams collaborate. Business needs often > change quickly in response to ever shifting digital markets, where new competitors can change a whole industry with a new app. In order to stay competitive, it's important > to support the rapid development and deployment of innovative services."

The architecture team evaluates the source and key systems necessary to expose. A few collaboration tools are involved in the building process, as well.

Stoplight Platform is used for API program consistency across the teams. Using the beta design libraries feature, the team can create consistency for their API language and shared assets.

“We use lots of collaboration tools like Miro, [hold] lots of Teams meetings and [use] various communication tools. And we also use Stoplight as our design tool … We use Stoplight design libraries to make sure we have a shared language to appreciate the APIs.”

The team of developers working with Fiserv is empowered through internal processes, enabling them to build systems that suit different clients. They gather domain feedback, the underlying system information gets converted into a customer data model used for modeling the APIs.

The design review process follows, ensuring data objectives are met by reviewing items such as invoice numbers, card numbers, addresses, and the different ways the business represents fees inside the data model. It is also important to have an API style guide that the company follows and further helps the team think of new versions and build different inputs.

“So we gather all of the domain feedback and all of the underlying system information and convert that into a customer data model, or what we call the experience data model. And we use that to model out our APIs themselves.”

As a team, it is vital to ensure that the clients are taken through the entire payment journey, helping them understand the different systems and how they work together, in order to facilitate faster, more successful implementation and get customers up and running faster.

Measurements and ROI

Customers are interested in understanding the benefits APIs will have on their businesses; the hard part is knowing what to measure to justify the value being added. API managers assess API consumption, API volumes, and how well new clients engage with Fiserv in order to measure success.

The speed of integration among clients is an important measure that helps understand the success of the different API products. So far, Fiserv’s API program and use of Stoplight has led to:

More API consumption and volume
Shorter time to onboard
Faster and more customer acquisition
Faster speed of integration
Fewer manual touch points
Higher engagement and developer satisfaction
Faster time to market
More consistency, shared language, and better governance

Advice for shifting culture toward design

First, it is important to have a leadership mandate that provides top-down support for a design-first approach. The management needs to realize the significance of adopting API technologies to enhance operations. The management, therefore, needs to provide tools and relevant resources to the team.

Secondly, API developers and product leads have to collaborate. Collaboration cuts down on development time and helps create APIs using already existing assets, saving money in the long run.

Developers also need to have a product mindset when dealing with APIs by treating the business as an opportunity through APIs. Constant learning needs to take place through reaffirming messages and fresh training. Customers need to be involved in the design and development processes of the API; their feedback will ultimately lead to API products that customers value and want to use.

Finally, getting the right people gets the job done; hire product managers, developers, and designers who are passionate about the whole process.

What's next for Fiserv?

Fiserv plans to develop more merchant payment technologies and innovations, continuously improve the developer experience, and explore new features to make consuming APIs easier.

“So we gather all of the domain feedback and all of the underlying system information and convert that into a customer data model, or what we call the experience data model. And we use that to model out our APIs themselves.”

Fiserv has the goal of creating more consistency, shared language, and better change management across the API program.

And they’re using API design - and Stoplight - to accomplish these goals.

Create consistency and enable collaboration at your organization. Include Stoplight to help your team go API design-first.

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Fiserv logo

Industry: FinTech Services

Location: Brookfield, Wisconsin

Employees: 44,000

Fiserv is a global fintech and payments company providing financial technology and payment solutions to some of the world's biggest companies for more than 35 years, including financial institutions, banks, and the shops that you use every day.

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