What is a REST API and API integration?
A REST API is a standardized interface through which software exchanges data and calls functions via HTTP. API integration refers to connecting such interfaces so that different systems communicate with each other automatically.
Also known as: RESTful API · web API · interface integration
Where a REST API is used
REST APIs are the connective tissue of modern software. They expose functions and data through clearly defined HTTP endpoints so that other applications can retrieve or change them programmatically – regardless of programming language or platform. Data formats such as JSON make the exchange uniform and easy to process.
API integration means connecting such interfaces meaningfully: a SaaS platform might connect an accounting system, a payment service or a CRM so that data flows automatically instead of being transferred manually. In mid-sized companies this removes many manual handoffs between systems and saves recurring work.
A practical example
An insurance platform needs to hand claims data over to a partner's core system. Via a REST API, the platform sends the cases in JSON format to a defined endpoint, receives a confirmation back and updates the status automatically. A manual export is no longer needed, and both systems stay synchronized in real time.
How it relates & how smiit uses it
REST is a widespread architectural style for web APIs, alongside variants such as GraphQL or SOAP; REST stands out through simplicity, broad support and good suitability for cloud services. smiit equipped Claimity AG's SaaS platform with REST APIs to connect it cleanly to existing systems. Running on Microsoft Azure with Azure App Service, secured via Azure Front Door and Keycloak for identity and MFA, the APIs enable automated, GDPR-compliant data exchange within the multi-tenant architecture.
Common mistakes & misconceptions
- REST is often equated with any HTTP or JSON interface, when it is actually an architectural style with concrete principles such as statelessness, a uniform interface and resource-oriented design.
- Many believe REST mandates JSON, although the style is format-agnostic and representations can equally be delivered as XML or other media types.
- It is frequently assumed that HTTP methods are interchangeable, whereas GET, POST, PUT and DELETE have clearly defined meanings, and GET should always be safe and free of side effects.
Frequently asked questions
What does REST mean in an API?
REST stands for an architectural style that addresses resources via HTTP methods such as GET, POST, PUT and DELETE. Data is typically exchanged as JSON, which makes the interface simple and usable independently of any platform.
Why is API integration important for companies?
It connects separate systems so that data flows automatically instead of being transferred manually. This reduces errors, saves time and is the basis for end-to-end digital processes and connected platforms.
What is the difference between REST and GraphQL?
With REST you query fixed endpoints that each return a specific data structure. With GraphQL the caller describes in a query exactly which fields they need. REST is simpler and broadly supported, while GraphQL is more flexible for complex, nested data queries.
How do you secure a REST API?
Common measures are encryption via HTTPS, authentication through tokens or OAuth, limiting the request rate (rate limiting) and careful validation of all incoming data. This ensures that only authorized systems access the right functions.
Related terms
Sources & further reading
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