Connecting systems: middleware, iPaaS or a direct integration? Choose in two minutes

The short answer. If you are connecting two systems with little logic, a direct integration is usually enough: a standard integration from your software’s app store or a direct API integration. For a few systems and simple steps, an integration platform (iPaaS) such as n8n, Make, Zapier or Power Automate is quick to set up. If you connect more than two or three systems, data flows both ways, or there is a lot of business logic or sensitive data in between, one layer of your own in the middle pays off: middleware. The chooser below shows you straight away what suits your systems, and why.

The three ways to connect systems

Direct integration. A standard integration that your software already offers, or an API integration from one system to the other. Quick, and cheap to maintain, as long as it stays at two systems and simple logic. You are, however, tied to what the integration does out of the box.

Integration platform (iPaaS). A middleware service in the cloud with ready-made connectors. You build integrations as flows, often without much code. For the differences between the platforms, see our comparison of n8n, Make, Zapier and Power Automate.

Dedicated integration layer. One layer in the middle that translates, checks, records and passes on data. More work up front, but you fully own it, and it stays manageable as systems are added.

Why separate integrations start to pinch

Every separate integration is a connection of its own, with errors of its own. With four systems there can be six of them, with six systems fifteen and with eight as many as twenty-eight. Through one layer in the middle you have exactly as many as you have systems: each system talks only to the layer. That is the whole idea behind system integration with a layer in between.

Middleware and iPaaS: what is the difference?

Middleware is software that sits between your systems and translates, checks and passes on data. An iPaaS is middleware as a cloud service: you rent the platform and set up the integrations with connectors. A dedicated integration layer is middleware that you own yourself. The difference lies in control, costs at scale and how well the work can be tested and monitored.

Integrating AFAS, Exact Online and Moneybird

These three Dutch accounting and ERP packages offer a standard API, so an integration is straightforward to build. How to connect them to your CRM is covered in our piece on Moneybird, AFAS and CRM. For EVOKE we built a finance platform on an integration with AFAS, with one data layer and controls down to individual transactions.

Five mistakes when connecting systems

Excel as the integration. An export that someone copies across every week is not an integration but a risk. Columns change and nobody notices.

Both ways without a source of truth. For each piece of data, decide which system leads, or systems will overwrite each other. This is called a single source of truth.

No logging or alerts. A flow can quietly stop when a system changes its API. Without an alert, you only notice when data goes missing.

Integrations without an owner. Who fixes it when it falters? Agree on that before it happens.

Every department with its own flows. Dozens of separate automations side by side become unmanageable. Once you have a few systems, one layer is easier to oversee.

Integrating for AI agents

If you let AI agents read or act in your systems, you want one place where you decide what an agent may see and do. There is an open standard for that: the Model Context Protocol (MCP). With your own MCP server on your integrations, you decide in one place what an agent may see and do, without every system having to be opened up separately.

Frequently asked questions

What is middleware?

Software that sits between your systems and translates, checks and passes on data, so applications work together without every system needing its own integration with every other system.

Is Zapier or Make enough?

Often, for simple, standalone steps between standard systems. With two-way traffic, a lot of logic, sensitive data or large volumes it becomes harder to manage, and an API change in one of the systems can quietly stop a flow.

How long does it take to connect two systems?

An integration between two systems with good APIs is often live within a few weeks. An integration layer under several systems is built step by step, one system at a time.

What does an integration cost?

That depends on the number of systems, the logic and how good the APIs are. We agree a fixed price up front for a clearly scoped integration. Book an intro call for an estimate.

Can I connect a system without an API?

Often, yes: through an export, an integration at database level or, as a last resort, screen automation. At In het Veld the target system did not (yet) have a public API. There, AI prepares everything and an employee checks the outcome before it is processed.