What is an API? A Non-Technical Explanation
An API (Application Programming Interface) is a defined way for two software systems to exchange data or functionality. One system sends a request, the other responds with a result. APIs are how your payment provider connects to your bank, how a Google Map appears on a contact page, and how your CRM syncs data with your accounting tool. The most common form is a REST API, which communicates over the web using standard HTTP methods.
An API is a way for two software systems to communicate with each other. When you pay online or log in with Google, an API is working in the background connecting those systems.
The restaurant analogy
Think of an API as a waiter in a restaurant. You are the customer, the application that needs something. The kitchen is the service that has what you need: data, functionality, or a computation. The waiter takes your order, carries it to the kitchen, and brings back exactly what you asked for. You never walk into the kitchen yourself. You interact with the menu (the API documentation), place an order (the API request), and receive a result (the API response). The kitchen’s inner workings stay completely hidden from you.
What an API actually does
An API defines a set of rules: what requests you can make, what format those requests must be in, and what the response will look like. A weather service API accepts a city name and returns current temperature and forecast data in a structured format. A payment API accepts transaction details and returns a confirmation or an error code. The underlying system, its database, its code, its infrastructure, stays hidden. You only interact with what the API exposes.
REST APIs: the most common form
REST (Representational State Transfer) is the most common architectural style for APIs on the web. REST APIs communicate over HTTP and use four standard methods: GET to retrieve data, POST to send data, PUT to update data, DELETE to remove data. Most modern online services offer a REST API. If your business uses a CRM, an accounting tool, or an e-commerce platform, it almost certainly has a REST API that allows other systems to read and write data.
Why APIs matter for your business
APIs let different systems in your business share data without manual copying. Your CRM can push new customer records to your accounting tool automatically. Your webshop can update inventory in real time as orders come in. Your reporting tool can pull fresh data from a source system on a schedule without anyone exporting and importing files. The alternative is manual work: exporting a CSV from one system and importing it into another, which is slow and error-prone.
Tools like Power Automate and n8n make API connections accessible without writing code. See how to create a scheduled flow in Power Automate for an example of pulling data from a source on a regular schedule, or how to use webhooks in Power Automate for event-driven API connections.
Our tip: When evaluating a new software tool for your business, check whether it has a documented public API. A tool without an API is an island: it can only exchange data through manual exports or proprietary integrations. A tool with a well-documented REST API can connect to almost anything.
Frequently asked questions
What does API stand for and what does it mean?
API stands for Application Programming Interface. 'Application' refers to any software application. 'Programming Interface' refers to the defined set of rules and methods through which that application can be accessed by other software. In practice, an API is a contract: if you send a request in this format, you will receive a response in this format. It defines what you can ask for, how to ask, and what you get back.
What is a REST API?
REST (Representational State Transfer) is the most common architectural style for web APIs. REST APIs communicate over HTTP, the same protocol your browser uses to load websites. They use four standard methods: GET to retrieve data, POST to send data, PUT to update existing data, and DELETE to remove data. Most modern online services, including CRMs, accounting tools, and e-commerce platforms, offer a REST API that allows other systems to read and write data programmatically.
Do I need to know how to code to use an API?
Not necessarily. Tools like Power Automate and n8n let you connect to APIs through a visual interface without writing code. You fill in the URL, choose the method (GET or POST), and map the fields. However, understanding what an API does and what the response format looks like helps you configure these tools correctly. For more complex APIs, some technical knowledge makes the process much faster.
What happens if a system I use does not have an API?
Without an API, data exchange between systems requires manual work: exporting a file from one system and importing it into another. This is slow, error-prone, and does not scale. Some older or specialized software also supports data exchange through file-based methods (SFTP, flat files) or database connections, which can be automated but are less flexible than APIs. When evaluating new tools, the presence of a documented public API is worth checking.