Toll4Europe: multi-country billing platform for European tolling

Challenge

Toll4Europe ran its billing on an aging monolithic system, while transaction volumes kept growing and new countries had to be onboarded on a tight cadence. Billing is the client's direct revenue stream, so every change had to preserve revenue assurance under continuous Deloitte audit. The platform needed to move to a modern, scalable architecture without ever interrupting invoicing or putting a single billing cycle at risk.

The DNA Solutions approach

We rebuilt the platform as a cloud-native, event-driven microservices architecture covering the full transaction lifecycle: ingestion, invoicing, payment requests and reconciliation. A real-time Apache Kafka pipeline decouples ingestion from invoice generation so the system absorbs volume spikes without slowing month-end runs.

Each country and sales partner is onboarded as configuration rather than a code rewrite. Keycloak handles authentication, the stack runs on AWS, and migration was phased so legacy and new systems ran in parallel with reconciliation before every cutover.

Outcomes

• Legacy monolith migrated to event-driven microservices with no billing disruption
• Live across multiple countries (Germany, Austria, Poland, Denmark, Belgium)
• Deloitte-audited revenue assurance maintained throughout
• Real-time pipeline from ingestion to reconciliation, new countries onboarded as configuration