With ever-changing business needs and increasing demand for digital products, building reusable application programming interfaces (APIs) is indispensable for any successful business. Reusable APIs offer several benefits, including increased productivity of digital development with speed, cost savings, reduced risks of cyberattacks and improved customer experiences. Creating new APIs involves time, effort and resources. Reusing APIs enables better control over who has access to business data and functionality via digital web assets, and the fewer they are in number, the easier management is.
Reusable APIs are essential for enabling two software applications to connect and exchange data or expose and share functionality. Two innovations have made reusable APIs integral. The first is increased usage and dependence on mobile applications; these apps source data by making remote calls to server-side stored data or business logic, made possible with APIs. The second is the advent of generative artificial intelligence (GenAI), which has increased the demand for retrieving and consolidating data from various sources in real time, which is only possible via reusable APIs (Figures 1 and 2).
Figure 1: Mobile apps accessing backend data using APIs
Figure 2: GenAI LLM models sourcing data from enterprise systems using APIs
These APIs fundamentally follow the principle of “build once and reuse multiple times for multiple business purposes.” They have commonality and standardization in their design—inclusive of companywide needs—allowing implementation throughout the organization. Reusable APIs hold minimal exclusive custom logic in their implementation base code, so personalization can be manipulated in each department as needed and offloaded to edge applications.
These reusable APIs are critical in combining ever-increasing connectivity needs with optimizing build cost and increasing delivery speed. If a company needs data or functionality to be available within several enterprise applications across the organization, it can lean on existing reusable APIs to expedite the process while saving money on time and resources instead of investing in new builds. These savings flow to the customer, allowing organizations to reduce prices and provide faster deliverables that meet or exceed expectations. One example of where reusable APIs are important is in microservices. Developing reusable APIs makes microservices easier to control and integrate with existing organizational architecture and applications, allowing companies to scale quickly and efficiently.
Operational Approach
Companies can identify the best approach for their operations and start building reusable APIs in five steps:
Figure 3: Five-step process to create reusable APIs
- Create a repository. List all existing integrations and APIs within the organization.
- Identify business data entities. These may include entities like accounts, invoices, or orders that are transferred using existing integrations and APIs.
- Prioritize data entities. Shortlist the first few data entities that are transferred most frequently between enterprise applications.
- Build common-canonical data structures. When creating data structures for the entities identified in the previous step, focus on designing a generic, all-inclusive payload data structure and refrain from implementing excessive custom logic in the API implementation.
- Build reusable APIs. Determine the most trusted source-of-truth systems of data for the respective data entities previously shortlisted and build canonical, structure-based, entity-specific reusable APIs that will deliver the data to enterprise systems.
Once the first batch of reusable APIs is constructed, organizations can retire existing exclusive and siloed APIs, replacing them with new reusable APIs. It is essential to periodically repeat these steps to build more reusable APIs that cover a broader range of business needs demanding data.
Mitigating Pitfalls
Cyberthreats are an ever-growing concern for organizations worldwide, yet many do not have adequate security measures (Figure 4). When organizations create reusable APIs, they restrict the number of overall digital web assets, reducing internet exposure. Building individual, siloed APIs for every need makes management and protection of those APIs challenging and increases the cost and resources needed to maintain cybersecurity.
Figure 4: Count of increased cyberattacks per Cisco report over six months
Developing reusable APIs requires considerable upfront build and implementation costs due to the time and effort involved. Decision-makers can expect more effort to be spent designing the data structure that APIs will interact with instead of the APIs themselves. Including these costs in the budget and implementation plan establishes appropriate expectations. Another pitfall of building reusable APIs is that they are built with base code standardization in mind; customizations and exclusive complex logic needed by different integrating applications must be performed at those respective sources and target applications instead.
Best Practices
There are two predominant best practices regarding reusable APIs to facilitate their adoption across current and future teams. First is ensuring highly accurate API specification documents are created using OpenAPI Specification standards from the design stage of an API build lifecycle. It is crucial for companies to keep the API specifications up to date with ongoing data structure changes by periodically reviewing and altering the specifications as needed. The second best practice is to ensure there are strong measures to enforce organization-wide API discoverability via an API registry or a catalog where all API documentation and other related details are easily accessible within the organization and to partners and shareholders.
Companies can ensure their APIs remain reusable as technology evolves by committing to periodic analytic reviews of their entire API repository. Organizations can continually add data points to existing APIs as IT applications and needs evolve, and reviews ensure their existing reusable APIs are caught up with the changing data landscape of their company to remain usable. Reviews also confirm the APIs include a broader standard range of data structure for respective data entities within the organization.
Managing APIs fuels growth—just over 12% during a four-year period, according to research from Boston University. In the future, digital products rendered via mobile applications will be in much higher demand. GenAI large language model (LLM) utilization is becoming mainstream and will continue increasing, warranting a greater need for reusable APIs to deliver the necessary data. Companies can implement an action plan to develop reusable APIs, saving time, effort and money while staying relevant and ahead of the competition.
