How it works
Apps are built for people: buttons, pages, menus. An API is the same service offered to other software. It publishes a list of requests it accepts, such as get this customer, create this post or generate text from this prompt, and the format each one must take. If a request follows the rules and carries a valid key, the service does the job and sends back a structured reply, usually in a format called JSON.
Three ideas cover most of what a beginner needs. An endpoint is the address for one kind of request. An API key is a secret that identifies you, so it must never be pasted into public code or shared in a screenshot. A rate limit is the cap on how many requests you may send in a period. Many paid APIs charge by usage, so the key is also tied to a bill.
Creators use APIs constantly without seeing them. Every integration in an automation tool is a wrapper around an API. When a tool has no ready-made integration, a generic HTTP request step lets you call the API yourself. AI models are offered the same way: you send a prompt to the model's API and get the reply back, which is how a model ends up inside your own workflow or product.
A worked example
You want an automation to write a first draft with an AI model that has no ready-made step in your tool.
- Create an API key in the model provider's console and store it in your automation tool's credentials, not in the workflow itself.
- Add an HTTP request step that sends your prompt to the provider's endpoint in the format its documentation shows.
- The reply comes back as JSON. You pick out the text field and pass it to the next step.
- You set a spending limit in the provider's console, because every request is billed.
An illustration, not a real account. Any numbers in it are made up to show the method, and are not benchmarks.
Common mistakes
- Exposing an API key. Anyone who has it can spend your money. Replace a key the moment it leaks.
- Confusing an API with a webhook. With an API you ask. With a webhook the other service tells you when something happens.
- Ignoring rate limits and errors. A workflow should wait and retry, not hammer the service.
Questions people ask
Do I need to code to use an API?
Not for most tasks. Automation tools wrap popular APIs in ready-made steps and offer a generic request step for the rest. Reading a little of the API's documentation helps a great deal.
What is an API key?
A secret string that tells the service who is calling. Treat it like a password: store it in a credentials manager, never in a public repository, and replace it if it is exposed.
Is using an API free?
It depends on the service. Some are free within limits, and many, including AI model APIs, bill by usage. Check the provider's pricing page and set a spending cap where one is offered.
Sources
MDN defines an API as a set of features and rules that exist inside a software program enabling interaction with it through software, as opposed to a human user interface.
Every link was opened on 13 October 2026. Products and policies change, so check the source before you rely on a figure.