toprentapp.com — fleet-management SaaS from zero to 500+ B2B clients

toprentapp.com is a web-based management and booking system for car rental companies: reservations, fleet, customer records, contracts, payments and reporting in one workspace. The product started from an empty repository in 2020 and by 2025 served 500+ corporate clients with sustained 20% year-over-year growth.

I led the distributed team at Laflei ltd (Rome) as Team Lead: architecture decisions, code review, mentoring, release process. The core is a Node.js / NestJS backend over PostgreSQL with Kafka for event-driven flows between booking, billing and notification services; the frontend is React and Next.js with GraphQL (Relay) and a custom UI library with dynamic theming for white-label deployments.

Beyond cars the platform serves bike, boat, scooter, camper and equipment fleets. Documents are the part clients notice first: multilingual contracts are generated automatically and signed digitally with OTP, so paperwork that used to take five minutes closes in about twenty seconds. Damage reports with photo and video, check-in/check-out checklists, GPS modules, a website booking widget and WhatsApp reminders complete the loop.

Integrations: Stripe for payments, Firebase for auth and push notifications, Cloudinary for media. Native iOS and Android apps sit on the same API. The main engineering challenge was keeping the platform stable under growing load while shipping features weekly — that is what the event-driven architecture and a strict review process were for.