Migrating a Logistics Platform from a Monolith to Event-Driven Services

A European logistics platform had outgrown its original monolith: every deploy risked the entire system, and the team that built it had grown from three engineers to twenty without the architecture keeping pace. A full rewrite was on the table, and it was the wrong call — the monolith handled real freight volume every day, and a big-bang replacement would have meant months of parallel systems and eventual breakage.

Instead, I led an incremental migration to event-driven services, starting with the shipment-tracking module that had the clearest boundaries and the most independent release cadence. Each service was extracted behind a message broker, with the monolith continuing to serve traffic for everything not yet migrated, so the system stayed live and correct throughout. Over five months, six services were extracted this way, each shipped and validated in production before the next began.

By the end of the engagement, deploy frequency for the extracted services had gone from once a month to several times a week, and a single team's mistake could no longer take down freight tracking for the whole platform.