Term · Integrations & automation

Middleware

Middleware is software in the middle. It receives data from one system, translates it and passes it on to the other.

Updated 7 October 20262 min read

In short

Middleware is software that sits between other systems. It accepts data, converts it to the form the other system expects and passes it on. That way, not every package has to talk to every other package separately.

What is middleware?

Middleware is software that sits between other systems and moves data from one to the other. Along the way it translates, so that each system receives the data in the form it knows.

You can think of it as an interpreter. The webshop speaks one language, the accounting system another. The middleware understands both.

How does middleware work?

Middleware fetches data or receives it, for example via an API or a webhook. Then it does three things:

Translating. A field is called ‘debtor’ in one package and ‘customer’ in another. Dates and amounts are written differently. The middleware converts it.
Passing on. It sends the data to the right system, or to several at once.
Keeping track. It records what worked and what did not. If something fails, someone gets a notification.

Example in an SME

Made-up example

A business has a webshop, a stock program, an accounting package and a CRM. If you connect each pair separately, you have six connections. With middleware in the middle, each package only talks to the middleware. If a package is added, you add one connection.

When do you need middleware?

With two systems, a direct API integration is usually enough. Middleware becomes useful when you connect three or more systems, when data needs a lot of translating, or when you want one place where you can see what goes wrong.

An integration platform is a form of middleware that you use as an online service. Middleware can also be custom-built for your systems. Read more about system integration, or see how I approach integrations and automation.

Frequently asked questions

Is middleware the same as an API?

No. An API is the entrance to one system. Middleware is software that uses the entrances of several systems to move data between those systems.

Where does middleware run?

On a server: in the cloud with a supplier, or with whoever builds and manages it for you. The middleware must be online for as long as your systems exchange data.

Does a small business need middleware?

Often not. With one or two integrations you can keep track without it. Middleware only becomes interesting when the number of systems and integrations grows.

Source for the definition: Microsoft Azure: What is middleware?. 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

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