Rentijer is not just another tool for landlords; it is a high-performance SaaS platform (Property Management System) designed to solve specific administrative challenges in the tourism market. Using Next.js 16, Bun, and Supabase, we built a system that automates critical processes such as guest registrations (eVisitor), document scanning, and real-time calendar synchronization. The result is a product that provides a native mobile experience without the need for app downloads, eliminating bureaucracy from the landlord's daily routine.
The Challenge: Technical Debt and Administrative Congestion
Property owners face a unique set of problems that traditional global PMS systems do not adequately solve:
Data Fragmentation: Manually syncing calendars from platforms like Airbnb, Booking.com, and Vrbo often leads to "double-bookings."
Bureaucratic Pressure: The legal obligation to register guests in state systems within 24 hours creates immense pressure, especially during late arrivals.
Tax Complexity: Calculating VAT on foreign platform commissions and tracking tourist fees often requires professional accounting assistance.
Legacy Solutions: Existing software is often slow, visually cluttered, and poorly optimized for mobile devices, which is critical for owners constantly on the move.
The project's goal was to develop a platform that is technically superior (speed, security, scalability) but user-invisible (ease of use in three clicks).
The Solution: The Future of the Web through Next.js 16 and PPR
To develop Rentijer, we chose a cutting-edge technology stack that allows for maximum development speed and top-tier performance. Using the Bun runtime, we achieved incredibly fast server function execution, while Next.js 16 enabled the implementation of Partial Prerendering (PPR).
PPR allowed us to deliver static parts of the interface (like navigation and layout) instantly, while dynamic data (like active bookings) is streamed from Edge servers directly into components. This eliminated traditional "loading" screens and achieved a zero-latency feel.
1. Unified Calendar: A Centralized Operating System
Instead of constantly switching between different screens, Rentijer offers a single "Single Source of Truth."
Engineering Execution: We implemented an advanced synchronization system based on the ical.js library. Vercel Cron Jobs periodically refresh data from all platforms, converting conflicting formats into a single unified object.
Real-time Updates: Using Supabase Realtime technology, every change in the database is automatically reflected on the user's calendar without needing a page refresh.
2. Self Check-in and OCR: The End of Manual Typing
The biggest leap in user experience was achieved through the automation of guest data collection.
Scanning System: We utilized native camera APIs within the PWA framework. Guests access a secure, one-time link to a scanning interface.
Technical Execution: The system uses advanced Optical Character Recognition (OCR) algorithms. Document images are processed via Next.js Server Actions, validated, and saved directly to the Supabase database. This eliminated human error and reduced the check-in process from 10 minutes to 30 seconds.
3. eVisitor Integration and Data Security
Government administration has become a background process.
Automated Registrations: Rentijer connects to the state systems, performing guest check-ins and check-outs with a single click. All data required for VAT forms and tourist tax slips are generated automatically based on entered bookings.
Security Protocols: Given the sensitivity of personal data, we implemented Supabase Row Level Security (RLS). Every database query is strictly isolated at the user level. All documentation is stored in an encrypted Supabase Storage system.
4. PWA Architecture: Native Experience without Installation
We chose a PWA (Progressive Web App) approach to bypass App Store limitations and provide users with instant access.
Technical Optimization: Instead of heavy libraries, we used native app/manifest.ts standards within Next.js 16. This ensured full compatibility with Turbopack and resulted in an app that weighs only a few kilobytes but behaves like a native application.
System Design: The interface is built using Tailwind CSS 4.x and shadcn/ui components, ensuring high contrast and readability even in bright sunlight.
Development Methodology and QA
Code quality and system stability are ensured through rigorous processes:
Strict TypeScript: The entire project is typed to prevent runtime errors in critical financial calculations.
Automated Testing: We use Playwright for end-to-end testing of critical paths (like booking creation and iCal sync).
Error Monitoring: Sentry tracks every anomaly in real-time.
CI/CD Process: Every Pull Request (PR) undergoes automatic validation and must reference a task ID with acceptance criteria.
Results: Digital Transformation in Practice
95% time savings on administration: The process from receiving a guest to their registration is reduced to less than one minute.
0% Double-bookings: The advanced sync engine completely eliminated scheduling errors.
Lighthouse Performance 90+: Thanks to Bun, Tailwind 4, and PPR technology.
Full Tax Readiness: Users receive generated VAT forms and payment slips ready for processing.
