Langfens — IELTS Preparation Platform

A comprehensive IELTS preparation platform with instant AI evaluation for Writing and Speaking. Built as 12+ microservices with .NET 8/9, featuring a YARP API Gateway, event-driven architecture via RabbitMQ, and full-text dictionary search with Elasticsearch. Includes a GPT-4o powered grading engine that scores writing in under 30 seconds, a Whisper-based speech-to-text pipeline for speaking evaluation, a spaced repetition vocabulary system (SM2 algorithm), and gamification with XP, streaks, and leaderboards. The platform also runs a local LLM chatbot (Qwen 2.5 via Ollama) for 24/7 student support.

Full-stack Developer