Wat is API-first ontwikkeling?

API-first development is one approach to making software. It means making the parts that let different programs talk to each other, the APIs (application programming interfaces), first. (before creating the rest). In API platform Postman’s 2025 State of the API survey, 25% of respondents’ organizations operated as fully API-first.

API-first-ontwikkeling is een belangrijk aspect voor zowel bedrijven als ontwikkelaars. Vroegtijdig focussen op API's is belangrijk omdat:

• Stroomlijn de ontwikkeling: Think of APIs as building blocks. Because they are designed for repeated use across different systems, they help engineering teams save time and optimize operational resources.
• Verhoog de flexibiliteit: API-first architectuur omvat modulariteit.
• Bevorder samenwerking: API-definities dienen als contract tussen ontwikkelaars.
• Stimuleer innovatie: APIs create partnerships and integration. Think of, Twilio, who offers APIs for making calls and sending messages as well as running video calls, all in the cloud.

An API-first approach has four key advantages and are stated in their simplest terms below:

Snellere time-to-market: Just get your product or feature into the hands of customers in less time.

Vergroot de schaal: Get Growing! and get your business the ability to handle more customers, work or data without ever breaking or slowing down.

Verbeter het onderhoud: Please do make software faster and less expensive and also, easier to update and keep running smoothly would be great.

Ervaring voor Ontwikkelaars: How easy and pleasant is it for a developer to use a tool platform, or understand your API documentation.

The OpenAPI Specification (OAS), previously called the Swagger Specification, is a common standard used to describe RESTful APIs. This includes a machine-readable way to define API endpoints, request and response formats, authentication methods, and more.

OAS in an API-first approach has the following advantages:

• Gestandaardiseerde Documentatie: OAS supports consistent API documentation.
• Geautomatiseerde Codegeneratie: Tools generate client and server code from an OAS document.
• Vereenvoudigd testen: OAS is useful to create test cases for your APIs.

In a design-first—or contract-first— the OpenAPI specification is written prior to code development, establishing a structural framework and enabling automated boilerplate generation (OpenAPI Initiative).

microservices is when several small self-contained pieces come together to provide the features of an application, similar to an assemblage of a puzzle.

This means they have to communicate with each other so that the process works well. And this is where APIs come in.

The API-first approach focuses on the design of cross-system communication before looking at core development. API-first and microservices tend to work together, since they are both connected to how application components integrate.

Here is a clean, easy-to-read table organizing those features: