EnglishAI
Adaptive English platform with speech assessment, placement testing and real-time pronunciation scoring.
Placement testing, pronunciation scoring, and lesson progress on a unified .NET backend.
Adaptive English testing, lesson progression, and real-time pronunciation scoring.
ASP.NET Core backend architecture, Azure Speech integration, and Redis caching.
Low-latency speech scoring under 120ms and resilient test session recovery.
The platform worked.
The onboarding didn't.
Telemetry revealed that legitimate mobile users were being dropped due to false-positive anti-cheat flags during placement tests. We refined the validation logic and enabled session recovery so students never lose test progress.
Three pieces, one flow.
Core API Architecture
ASP.NET Core REST endpoints for placement tests and lesson tracking, backed by PostgreSQL and Redis read caching.
Speech Evaluation Pipeline
Azure Speech STT and pronunciation assessment with MD5-hashed Redis caching, cutting duplicate third-party costs.
Resilient Session Recovery
State persistence and idempotent resume logic allowing students to resume interrupted tests without losing progress.