API
An API (application programming interface) is a set of rules and protocols that lets different software applications communicate and share data. It acts as an intermediary—for example, when an online store shows a shipment's status, its website requests the latest data from the carrier through an API. The most widely used types are REST APIs and GraphQL, which power everything from payment gateways and CMS integrations to AI tools.
APIs are the backbone of the modern internet, and their importance to business keeps growing:
- APIs generate revenue: according to a MuleSoft survey (conducted with Vanson Bourne and Deloitte Digital, 1,050 IT leaders from companies with 1,000+ employees, October–November 2024), APIs and API-related implementations now account for 40% of company revenue – up from 25% in 2018 (MuleSoft – 2025 Connectivity Benchmark Report)
- REST dominates, but the mix is diversifying: Postman's survey of 5,700+ developers and API professionals (2025) shows that 93% of teams use REST APIs, while adoption of complementary technologies is growing—webhooks (50%), WebSockets (35%), and GraphQL (33%) (Postman – 2025 State of the API Report)
- An API-first approach pays off: in Postman's 2024 survey, 74% of respondents say they put APIs first in development. The result? 63% of developers can ship a working API within a week, compared with 47% the year before (Postman – 2024 State of the API Report)
- Integration is a critical weak spot: although the average enterprise uses more than 900 applications, only 28% of them are connected through APIs. Just 2% of organizations have integrated more than half of their applications (MuleSoft – 2025 Connectivity Benchmark Report)
- AI needs APIs: 89% of developers already use generative AI tools in their daily work, and nearly one in four developers (24.3%) designs APIs specifically for AI agents – a sign of a major shift toward APIs consumed by machines, not just people (Postman – 2025 State of the API Report)
FAQ
What's the difference between REST APIs and GraphQL?
A REST API uses fixed endpoints—each one returns a predefined data structure. GraphQL, by contrast, lets the client specify exactly what data it needs and get it in a single query. According to Postman's survey (5,700+ respondents, 2025), REST still dominates with 93% adoption, while 33% of teams use GraphQL—typically where they need more flexible data handling, such as in mobile apps or with a headless CMS (Postman – 2025 State of the API Report).
Why are APIs important for websites?
APIs let a website communicate with external services—a payment gateway, a CRM, an email tool, or analytics software. Without APIs, every one of these features would have to be built from scratch. MuleSoft data (1,050 IT leaders, 2025) shows that IT teams spend 39% of their time building custom integrations, which underlines the value of ready-made API solutions (MuleSoft – 2025 Connectivity Benchmark Report).
What is a headless CMS and how does it relate to APIs?
A headless CMS is a content management system that separates managing content from displaying it. It delivers content through an API, so the same content can appear on a website, in a mobile app, and on other platforms. 44% of enterprises have already adopted this approach for the speed and scalability it offers.
Sources:
- Postman – 2025 State of the API Report – a survey of 5,700+ developers and API professionals, with data on REST, GraphQL, and AI adoption
- Postman – 2024 State of the API Report – a survey of 5,600+ respondents, with data on the API-first approach and monetization
- MuleSoft – 2025 Connectivity Benchmark Report – 1,050 IT leaders, in collaboration with Vanson Bourne and Deloitte Digital, with data on API revenue and integration
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