API development that reliably connects your systems

That depends on how many systems are involved and how well their interfaces are documented. Individual, clearly defined connections can be implemented in the Starter package from €2,500, backends and integrations of several systems in the Professional package from €8,000. Complex system landscapes are quoted individually in the Enterprise package.

A single connection between two well-documented systems is often productive within a few weeks. When data cleanup, multiple systems or coordination with third-party providers are required, we plan in stages. We give you a realistic estimate of the timeframe after the system analysis.

After the free initial consultation we create a system map and an integration concept. We then develop, test with approved real data and take the interface live after your acceptance. In operation, we monitor the data flows.

Then we examine alternatives such as database access, file exchange via CSV or XML, email import or add-on modules offered by the vendor. Not every solution is equally robust – we show you the pros and cons and recommend the most stable route.

We transmit data encrypted, secure access with methods such as OAuth 2.0 or API keys and grant only the permissions an interface really needs. Access is logged so that every data flow can be traced.

Vendors occasionally change their interfaces or retire old versions. Under a maintenance contract, we keep an eye on such changes, adapt your integrations in time and respond to error messages from monitoring.

An API is a defined interface through which two programs exchange data without anyone having to transfer it by hand. With a REST API, this happens via web addresses and standardized requests to retrieve, create, change or delete data, usually transmitted in JSON format. Access keys or methods such as OAuth 2.0 ensure that only authorized systems get access.

The frontend is everything users see and operate – interfaces, forms, tables. The backend works in the background: it stores data, checks permissions, runs business logic and provides interfaces for web app, mobile app or partners. At Nano Concepts we develop both, so frontend and backend fit together cleanly.

Yes, we check the right route for it – for example the official interfaces and data formats of the respective vendor or existing add-on modules. For some vendor interfaces, a registration or certain licenses are required; we clarify that with you before the project starts. That way you know in advance which route is technically stable and economically sensible.

That depends on how you create and receive invoices today. Since 2025, companies in Germany must be able to receive e-invoices in the B2B sector, while the obligation to send them is being introduced in stages. We check whether your systems already support formats such as XRechnung or ZUGFeRD or whether a connection is needed. This does not replace legal or tax advice.

A backend includes the database and data model, the business logic, a documented API, user and permission management, and background processes such as email delivery or scheduled syncs. On top of that come hosting, automated deployments, logging and monitoring. We plan these building blocks so that your backend can grow with increasing usage and new applications.