Duolingo English Test leverages AWS services across four phases: account isolation via CloudFront and IAM, test delivery through ECS/EKS with real-time proctoring, response capture and ML-powered scoring using SageMaker, and secure result storage in S3. The sequence diagram traces test taker interactions from session setup through CloudFront and WAF, compute orchestration via ECS/EKS, state management in DynamoDB, speech synthesis via Amazon Polly, and ML inference through SageMaker. This architecture demonstrates how to build a high-security, low-latency assessment platform that isolates user sessions, captures responses in real time, and applies machine learning for instant scoring. Fork this diagram on Diagrams.so to customize for your own proctored testing or certification platform. The four-phase design separates concerns—isolation, delivery, scoring, and archival—enabling independent scaling and compliance auditing.