Interface

An interface in software is the connection through which two systems exchange data automatically under fixed rules. It defines which data flows, in which format, in which direction and how often.

Explanation

Without an interface, programs work side by side. Employees transfer orders into the ERP by hand, type invoices into accounting or maintain customer data twice. An interface takes over this transfer. It reads data from system A, converts it into the format of system B and writes it there.

Technically there are several ways. Most often an interface runs through the API of the systems involved. But it can also run through files such as CSV or XML, through direct database access or through an export and import folder. Every interface comes with a data mapping, meaning the assignment of fields, and with rules for errors, retries and duplicates.

Example from everyday integration work

A wholesaler sells through an online shop and manages stock and invoices in an ERP. The interface transfers every new order from the shop into the ERP. In the opposite direction it reports stock levels and shipping status back to the shop. Nobody has to retype orders any more, and the shop does not show items as available that sold out long ago.

How it differs from related terms

• API: a particular kind of interface that a system provides for programs.
• Middleware: an additional layer that mediates between several systems. A direct integration does without it.
• iPaaS: a platform on which you assemble connections from building blocks.
• Bidirectional: an interface that works in both directions.

Relevance to our services

We program direct integrations from system A to system B, at a fixed price and with code that you own. The page Have an integration programmed gives an overview. For ongoing operation with monitoring, see Operation and monitoring.

Updated: 10/20/2026