GEMonitor - OSRS Trading Terminal
Fintech Grade Grand Exchange Analytics Platform
A professional trading terminal for Old School RuneScape featuring realtime flip scanning, FIFO trade matching, portfolio tracking with unrealized P&L, session based analytics, social leaderboards, and 16+ money making calculators all wrapped in a mobile first, fintech inspired interface.
Project Overview
Role: Full-Stack Engineer
Duration: Ongoing (WIP)
Team: Solo Project
Year: 2025
Technologies Used
Project Details
A production ready alternative to legacy OSRS trading tools like GE Tracker, built with modern web technologies to deliver superior UX and advanced analytics. GEMonitor combines real time Grand Exchange price data from the OSRS Wiki API with intelligent FIFO buy/sell matching algorithms, automatic 2 hour session grouping, portfolio tracking with costbasis analysis, and a comprehensive suite of calculators covering everything from High Alchemy to Herblore. The platform implements a freemium monetization model with Row Level Security policies in Supabase, planned RuneLite auto sync plugin integration, and social features including public profiles and four distinct leaderboard types all delivered through a responsive, TradingView inspired interface built with Next.js 16, React 19, and Tailwind.
Challenge
Build a competitive trading platform that matches feature parity with established tools while differentiating through superior mobile UX, advanced analytics, and social features. Implement complex FIFO matching logic for accurate profit tracking, design an intelligent flip scanner with probability weighting, create 16+ data driven calculators with real time price integration, build a scalable freemium architecture with Row Level Security, and deliver a professional fintech grade interface that works seamlessly across all devices all while using the same public price data as competitors.
Solution
Developed with Next.js 16 App Router leveraging server components for optimal performance, React 19 for concurrent features, and Supabase PostgreSQL implementing Row Level Security. Built intelligent FIFO algorithms that automatically pair buy/sell trades for accurate realized and unrealized P&L calculation. Implemented session based analytics that auto groups trades into 2 hour windows to identify performance patterns. Created an advanced flip scanner with multi dimensional filtering (ROI, volume, margins, buy limits) and probability weighted scoring. Designed 16+ calculators powered by static JSON recipe data and real time GE prices with 30 second ISR caching. Integrated OSRS Wiki API for 5 minute price updates, volume tracking, and historical timeseries. Built social features including opt in public profiles, four leaderboard types, and achievement badges. The platform is currently in WIP status with core features complete but payment integration and RuneLite plugin pending.
Key Features
- Log trades and see profit/loss calculated automatically with GE tax
- View trading sessions grouped by time to spot your best hours
- Track portfolio value with per-item cost basis and performance
- Find flips using scanner filters for margin, ROI, volume, and buy limits
- Calculate GP/hour for 16 skills with live prices
- Compare rankings on opt-in weekly and all time leaderboards
- Analyze price history with candlestick charts at multiple timeframes
- Set alerts for price movements on watched items
- Export trade history as CSV or JSON
Results & Impact
- ✓
Implemented FIFO algorithm that correctly pairs trades across partial fills and split orders
- ✓
Built session detection using timestamp gap analysis to auto-group trading periods
- ✓
Created shared recipe schema powering 16 calculators with real time price injection
- ✓
Designed composite scoring formula weighting ROI, volume, buy limits, and margin stability
- ✓
Integrated OSRS Wiki API with SWR caching to respect rate limits while staying fresh
- ✓
Architected freemium access tiers using Supabase Row Level Security policies