Interface (API)
An interface (API, application programming interface) is a defined connection through which two software systems exchange data automatically — such as a shop with accounting or a CRM with the website.
Without interfaces, data is entered twice: orders retyped, customer data copied, lists emailed. That costs time and creates errors.
Modern systems usually provide documented interfaces; where they do not, data can be connected via exports, automation tools such as n8n or Make, or custom services.
A practical example is Zarrillo’s online shop: via BaseLinker it is connected to Amazon, OTTO, Kaufland, eBay as well as Instagram and TikTok Shop.
What to look out for
- Write down which data is entered twice or copied today — that is where the biggest potential lies.
- Check whether the systems involved offer documented interfaces.
- Define which system is leading for which data so there are no contradictions.
- Plan for failure cases: what happens if a system is unavailable?
- Manage credentials and keys securely and renew them regularly.
Common mistakes
- Two systems overwrite each other because it is unclear which one leads.
- Transfer errors go unnoticed because nobody is notified.
- API keys sit in plain text in spreadsheets or emails.
Frequently asked questions
It depends on how well the systems involved are documented, how many data types are transferred and how failure cases should be handled. After a brief review, the effort can be estimated concretely.
Not always. Many connections can be built with automation tools such as n8n or Make; custom development pays off for complex, business-critical or very frequent transfers.