Waqar Bin Kalim

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• 4 min read

Holiday Optimizer

Holiday schedule optimizer - helps maximize time off by strategically planning holidays

Technologies Used

React Next.js TypeScript AWS Lambda S3 Stripe Cloudflare
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Holiday Optimizer Application Holiday Optimizer - Maximize your time off with strategic planning

The Holiday Optimizer is a web application designed to help professionals maximize their vacation time by strategically planning holidays around public holidays and weekends. By intelligently analyzing holiday calendars and suggesting optimal leave dates, the application helps users get the most value from their annual leave allowance.

The Challenge

Many professionals struggle to make the most of their annual leave. With limited vacation days and numerous public holidays scattered throughout the year, it can be difficult to identify the best times to take leave to maximize consecutive days off. The challenge was to create an intuitive tool that analyzes holiday patterns and provides actionable recommendations.

The Solution

I built a serverless web application using modern cloud technologies and a React-based frontend. The application allows users to input their available leave days, select their region for accurate public holiday data, and receive optimized suggestions for when to take time off to maximize consecutive days away from work.

Key Features

  • Intelligent Leave Planning: Algorithms analyze public holidays and weekends to suggest optimal leave dates
  • Multi-Region Support: Accurate public holiday data for multiple countries and regions
  • Visual Calendar Interface: Interactive calendar showing suggested leave periods and resulting days off
  • Efficiency Metrics: Clear visualization of how many total days off result from each leave day used
  • Calendar Export: Paid feature to export planned holidays as .ics files (currently available to U.S. customers)
  • Privacy-First Design: All calculations run locally in the browser with data stored in local storage
  • Responsive Design: Seamless experience across desktop, tablet, and mobile devices

Technical Implementation

The application follows a privacy-first, browser-based architecture:

  • Frontend: Built with Next.js and React, utilizing TypeScript for type safety and Tailwind CSS for styling
  • Local Processing: Holiday calculations run entirely in the browser using the bundled date-holidays library
  • Data Storage: Plans, preferences, and custom time-off data are stored in browser local storage
  • Hosting: Deployed on Cloudflare Pages for fast, global content delivery
  • Calendar Export: AWS Lambda generates .ics files stored temporarily in private S3 buckets (48-hour retention)
  • Payments: Stripe Checkout processes calendar export purchases
  • Email Delivery: Resend sends download links for purchased calendar files
  • Analytics: PostHog provides privacy-focused, consent-based usage analytics
  • CI/CD: Automated testing and deployment workflows

The holiday optimization algorithm runs locally in your browser, analyzing public holidays, weekends, company policies, and user preferences to generate personalized recommendations. No personal data or holiday requests are sent to external APIs.

The Outcome

The Holiday Optimizer has helped users make better use of their annual leave allowance. The intuitive interface and intelligent recommendations have received positive feedback from users who appreciate the data-driven approach to vacation planning.

The Takeaway

Building the Holiday Optimizer reinforced the importance of solving real-world problems with elegant technical solutions. The project deepened my understanding of serverless architectures, algorithm design, and building user-centric applications. It demonstrated how cloud technologies can power responsive, scalable applications that provide genuine value to users.