An API is an agreed interface through which systems exchange data or actions. A website needs one, for example, when products come from an inventory system, leads go to a CRM, or users log in through an external service.
A simple example
A shop asks an ERP for the current stock level. The website sends a request, the API checks permission and parameters and returns a structured response. The interface translates that response into “available,” “only a few left,” or an error message.
When an integration makes sense
- the same data is currently maintained manually in several places
- stock, prices, or status must stay up to date
- an external service is part of the user journey
- handover errors cause measurable effort
- automation regularly saves repetitive work
Seven questions before committing
- Is there current documentation?
- Which authentication is used?
- Which data may be read or written?
- Which limits and costs apply?
- How are errors and timeouts handled?
- Which system is the leading data source?
- Who monitors changes to the API?
The invisible part: error cases
A demo usually shows only the success case. Production needs timeouts, retries, logging, understandable feedback, and protection against duplicate actions. Sensitive keys belong on the server, not in public browser JavaScript.
NJUME builds interfaces within custom websites, portals, and automations. For commerce integrations, also see the Shopify agency page.
Primary sources and documentation
As of: August 29, 2026. This article describes a professional decision framework and is not a guarantee of revenue, rankings, or results.