Car rental · Next.js

TransilvaniaCar — a three-language car rental site with instant, server-checked quotes

transilvaniacar.com ↗

2 days ago·

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·3 min read

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Context

TransilvaniaCar rents cars in Cluj-Napoca, Târgu Mureș, Sibiu and Brașov. I've worked on their site since 2023, and in November 2026 it went through a large redesign and refactor: a new look, a new booking flow, passwordless admin login and a map of the pickup cities.

The problem

Customers come from Romania and abroad, so the site has to work in Romanian, English and German, with translated URLs. They want to see a real price immediately, and that price depends on many things at once: rental length, season, pickup and return locations, out-of-hours pickup, extras and mileage packages. The staff, meanwhile, need one place to manage the fleet, prices, locations, extras, customers and bookings.

What I built

• A public site in three languages (Romanian at the root, English and German under their own prefixes, with localised paths such as /masini, /cars, /autos): homepage with "how it works" in three steps, FAQ, Google rating and testimonials, car pages, a contact page with spam protection and a map of the four cities.
• A travel blog with guides on the Transfăgărășan, castles, itineraries and airports, written in MDX.
• A three-step booking wizard — dates and locations, car and extras, customer details — with filters built from the actual fleet. Its state lives in a store kept in session storage, so the booking survives a page refresh.
• An admin panel with stat cards, a bookings chart and data tables for cars, extras, locations, customers and bookings. Staff move each booking from waiting to approved, completed or rejected.

Under the hood

• One pure pricing function combines day-range tiers, seasonal periods, a relocation fee when the return location differs, an out-of-hours fee, extras and mileage packages. The browser uses it for the instant quote; the server runs the same calculation and rejects the booking if the totals differ.
• Money is handled in cents through a small Money class.
• Bookings are idempotent: a request ID stops a double submit from creating a second booking, and each booking stores a snapshot of the car and fees at the time it was made.
• Admin login uses Better Auth magic links with sign-up disabled; the Next.js 16 proxy handles both language routing and a quick session check.
• Translations live in JSON files synced with Crowdin; car descriptions are stored per language.
• 13 Jest suites cover the quote, money, price tiers, durations, working hours, the booking store, consent and validation.

Result

Customers get a final price as they choose, in their own language, and the price they see is the price that's stored. Staff manage the whole rental business — fleet, prices and bookings — from one panel.

Stack

Next.js 16, React 19, TypeScript, Prisma 7 on PostgreSQL (Supabase), Better Auth, next-intl, Zustand, react-hook-form, zod, Recharts, Leaflet, Brevo, Cloudflare Turnstile, Crowdin, Jest.