Software engineering · Kosovo

APIs & integrations

A connected product depends on clear agreements between systems. An app may create a request, a workspace may review it and another service may return a result. PREJ develops APIs and backend integrations that make those responsibilities explicit. We work with Node.js, NestJS, Python and relational data tools, choosing the implementation around the existing systems, the workflow and the maintenance requirements.

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What we can build together

Define the contract before connecting the pieces

We establish which system owns each record, what an operation is allowed to change and which response the caller can rely on. Request validation, authentication and role-based permissions are part of that contract. Clear boundaries make it easier to connect a mobile app, a web portal and an administrative workspace without letting each interface invent a different version of the same business rule.

Treat failure as part of the workflow

A remote service can be unavailable, a submitted file can be invalid and the same request can arrive more than once. We discuss these cases alongside the successful path. Depending on the integration, the design may need duplicate protection, deliberate retry rules or a visible human review step. The right behaviour depends on the operation; retrying a status lookup is not the same as repeating a state-changing action.

Keep data and operational decisions traceable

Integration work is not just moving fields between endpoints. Records need useful relationships, consistent states and clear ownership. We map how information enters the system, how it is validated and what a person needs to inspect when something goes wrong. Third-party access, provider limits, credentials and deployment requirements are identified early. We do not promise an integration before the external system’s supported access has been checked.

A scope you can review

An interface and data-flow map with ownership and access boundaries.
Agreed endpoints or connectors with validation and explicit responses.
Priority success and failure checks, integration notes and a handover plan.

From requirements to a working system

The starting point is a concrete workflow and the interfaces already available. We review the dependencies, agree a bounded integration and implement it in steps that can be checked independently. Tests should cover the states that affect the user or operator, not only whether an endpoint returns a response. Human engineering judgment remains responsible for permissions and release decisions; AI assistance does not remove those responsibilities.

Related development work

TORQENIX

TORQENIX is a B2B ECU file-service platform for professional workshops. Dealer accounts, original-file uploads, order tracking, messages and a credit ledger connect to an administrator-led review and release workflow. It provides a concrete example of files, permissions and state changes that need to agree across an application. Calibration is performed outside the platform, and live bank payments are not yet enabled. Those boundaries remain explicit in the portfolio.

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Practical questions

Can you connect a third-party service?

First we verify its documented API, permitted access and the account capabilities available to you. Authentication, provider restrictions and operational requirements determine what is feasible. Unsupported access is not replaced with a hidden workaround.

Do we need to replace our existing database?

Not automatically. We examine the current data model and the new workflow first. A connector, a limited extension or a migration may each be appropriate; the choice should follow the constraints rather than a preferred technology.

Start with the workflow, not a feature list.

Tell us who will use the product, what they need to do and which systems already exist. We will discuss the scope, constraints and next useful step.