Term · Integrations & automation
API
An API is the fixed entrance to a software package. Other software can retrieve and send data there.
In short
API stands for application programming interface. It is a fixed entrance to a software package, with agreements about which data other software may request or send. An API is not an integration in itself: an integration connects the APIs of two systems.
What is an API?
An API is a fixed entrance to a software package, through which other software can request and send data. The abbreviation stands for application programming interface.
You work with a package via the screen: you click and you type. Software does not work via that screen, but via the API. The API sets out which data you can request, such as customers or invoices, and in what form you get it back.
How does an API work?
An API works with questions and answers. Another program sends a request, for example: give me today's invoices. The API first checks whether that program has access. Then it sends the data back, in a fixed structure that software can read.
You arrange access with an API key or with a login via OAuth. That way you decide which software may see and do what.
An API only answers when you ask something. Do you want a package to report by itself that something has changed? Then you use a webhook.
Example in an SME
Made-up example
An installation company schedules jobs in a planning program and invoices in an accounting package. Both packages have an API. As a result, a piece of software can retrieve a completed job from the planning and turn it into a draft invoice in the accounts.
That piece of software is called an API integration. The API is the entrance. The integration is the connection between two entrances.
What should you watch for?
- Is there an API? Many business packages have one, but not all. Sometimes the API comes with a more expensive subscription, or you first request access from the supplier.
- What is in it? Not every API gives access to all data. Check in advance whether the data you need is in it.
- Is there documentation? A good API has a manual for developers. It states what is possible and what is not.
Do you want to know whether your packages can be connected via their API? Read how I approach integrations and automation. You can find more explanation in What is an API integration? Explanation for business owners.
Frequently asked questions
Is an API the same as an API integration?
No. An API is the entrance to one system. An API integration uses the entrances of two systems, so that data goes from one to the other.
Do you need to be able to program to use an API?
To build something with it yourself, usually yes. With an integration platform you use many APIs via ready-made blocks, without programming. For a custom integration, you bring in a developer.
Is an API safe?
An API is as safe as the agreements around it. Give each integration its own access, with no more permissions than necessary. And do not store keys in a shared email or chat.
Source for the definition: MDN Web Docs: API (in English). Consulted on 7 October 2026.
Written by Bart van Engelenhoven Founder of Uniekaiconsultancy in Ede, the Netherlands. Bart analyses how SMEs work and builds software, integrations and AI applications himself. Last updated: 7 October 2026
Read more
Term
API integration
What is an API integration? Two systems exchange data themselves via their API, so nobody has to retype it. With an example and what to watch for.
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API key
What is an API key? A secret code that gives software access to another system. How it works, and how to handle it safely.
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Webhook
What is a webhook? A signal a package sends by itself as soon as something changes, so another system can carry on. With an example and points to watch.
Read moreNext step
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