Muhammad Ahsan

Designed BFF session architecture with OAuth PKCE, opaque HttpOnly session cookies, Redis sliding-window store, and event-driven bulk invalidation

Built stateless file server with object storage integration, streaming SHA-256 dedup, presigned JWT download URLs, and tee-stream watermarking pipeline

Developed Elasticsearch indexing with RBAC access filtering via pre-computed user access arrays injected at query time.

Implemented two-stage RabbitMQ fan-out pipeline processing multiple events with cascade detection and per-entity distribution

Established shared GraphQL CRUD factory, background job infrastructure, and Carbone templating integration adopted across 7 services

Developed multi-role React dashboard with distinct views and access flows for four user roles

Designed MongoDB schema and REST API routes with role-based access control using Node.js and Express

Integrated Microsoft SSO via MSAL for authentication across all user roles

Designed BFF session architecture with OAuth PKCE, auth service owns the full OAuth exchange, downstream services validate via shared Redis lookup, eliminating per-request DB queries and token exposure to the browser

Engineered stateless file server using presigned JWT over opaque tokens to eliminate DB dependency, streaming upload with no RAM buffering, post-upload tenant-scoped SHA-256 dedup, atomic cache writes via temp-file rename, and two-layer path traversal protection

Architected Elasticsearch indexing pipeline with document-level RBAC enforced via pre-computed access arrays at query time

Implemented RabbitMQ event infrastructure for async processing, cascade fanout and cross-org mail distribution

Developed multi-tenant embeddable chatbot widget in SolidJS deployed via script tag with per-tenant runtime configuration

Widget supports conversational AI, meeting scheduling, and automatic Freshdesk ticket creation on unresolved issues, backed by RAG pipeline and agentic tool calls

Delivered analytics dashboard tracking token consumption, response latency, hallucination rate etc.