SNCF
Ghazi Ben Ahmed
SNCF
Staff software engineer · 2022–2023
API response time cut by 60%, at 1M+ requests a day
Rail operations data ran through a legacy monolith, with every system tied to the others.
My part
I architected its replacement: event-driven microservices in Scala on AWS, designed by domain.
What the team delivered
Off the monolith with zero downtime
500GB of rail operations data a day
Coupling between systems cut by 80%
€200K a year saved on AWS
Stack: Scala · AWS MSK · Lambda · Terraform · Domain-driven design · Hexagonal architecture
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Posted Oct 24, 2026
Architected event-driven microservices to replace a monolith, cutting API response time by 60% at 1M+ requests/day and saving €200K/year on AWS.
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