SK
api-gateway-auth
OAuth2 authorization server and Spring Cloud Gateway: scope-based access, per-client rate limits, circuit breakers and correlation ids.
Live on GitHubSameer Khan Pathan
Senior Java Full Stack & Cloud Engineer, Dallas, TX
10+ years building reliable enterprise software.
Senior Java Full Stack Engineer with 10+ years of experience delivering enterprise applications across retail, payments, healthcare, travel and SaaS. I specialize in Java, Spring Boot, Angular, React, event-driven systems and cloud platforms.
Try the order saga
Interactive browser simulation of the order saga. No backend services or real payments are called.
The payment simulator declines anything over $1,000, so you can watch the compensation path.
Place an order to see each event as it moves between services.
Selected work
Six independent engineering projects, with three featured below. Explore working interfaces, migration decisions and service consistency, then inspect the source and automated checks.
01 / FULL-STACK OPERATIONS
Signal Desk
A focused incident operations workbench. Find the signal in a busy queue, investigate an incident, advance its lifecycle and inspect the audit trail.
- React 19
- Java 17
- Spring Boot
- Spring Security
- REST API
- Vite
Public demo: synthetic browser data. The repository includes a separate local Spring Boot API.
DESIGN FOR THE PERSON ON CALL
- Permissions with a clear boundaryViewer and operator modes in the UI; server-side role checks and CSRF protection in the local API.
- No silent stale updatesExpected-version checks reject conflicts. Successful state changes append an audit entry with the authenticated actor.
- The states around the happy pathSearch, combined filters, pagination, read-only access, empty results and failure feedback.
02 / SYSTEM EVOLUTION
Java Modernization Playbook
Change an implementation without quietly changing the business contract. A runnable pricing migration with characterization tests, shadow comparison, stable canary routing and rollback.
- Java 17
- JUnit 5
- BigDecimal
- Strangler pattern
- Canary routing
- GitHub Actions
Browser lab: illustrative simulation. The repository contains the executable Java implementation.
CHANGE THE ENGINE. KEEP THE CONTRACT.
- Characterize before replacingExplicit boundary cases and a seeded 10,000-request comparison check discount, rounding and shipping behavior.
- Compare before promotingShadow mode preserves the legacy response. Stable SHA-256 buckets make canary cohorts repeatable.
- Know what rollback cannot undoRead-only fallback and configuration swaps are implemented; data migration and destructive-schema recovery are documented boundaries.
03 / DISTRIBUTED CONSISTENCY
Commerce Order Platform
Order and payment microservices that stay consistent without distributed transactions. An order is accepted, payment is attempted, and the order is either confirmed or cancelled, coordinated through Kafka with a choreography saga.
- Java 21
- Spring Boot 3
- Apache Kafka
- PostgreSQL
- Flyway
- Redis
- Docker
- Kubernetes
- GitHub Actions
- Business changes and events commit togetherA transactional outbox writes each event in the same database transaction as the order, then relays it to Kafka.
- Design for duplicate deliveryAPI idempotency keys and database constraints demonstrate retry handling. Payments use a simulator; real providers also require provider-side idempotency and reconciliation.
- Failures compensate cleanlyA declined payment cancels the order automatically; poison messages go to a dead-letter topic instead of blocking a partition.
- Operational foundationsHealth probes, deployment manifests, metrics and CI provide a starting point. Production readiness still requires deployment, security, load and recovery validation.
realtime-event-analytics
Kafka events into Spark Structured Streaming and BigQuery, with an Airflow daily rollup, data-quality gates and Terraform.
Live on GitHubcloud-platform-terraform
Reference Terraform modules for private GKE networking, workload identity, separate environment configurations and Argo CD GitOps.
Live on GitHubProfessional experience
10+ years delivering enterprise software across multiple industries. Public GitHub repositories are independent demonstration projects, not proprietary client source code.
Senior Full Stack Developer · Target
Retail and e-commerce platforms using Java 17, Spring Boot, Angular 16, Kafka and AWS.
Senior Full Stack Developer · Visa
Payments and financial services with Java, Spring Boot, React, TypeScript, Azure and RabbitMQ.
Java Full Stack Developer · Cigna
Healthcare applications with Spring Boot, Angular, GCP and HL7/FHIR integrations.
Java Full Stack Developer · United Airlines
Travel, booking and loyalty systems using Java, Spring Boot, Angular and AWS.
Software Developer · Zoho
Enterprise applications using Java, Spring MVC, Hibernate, JSP and Servlets.
What I work with
Full stack across the Java ecosystem and all three major clouds, with most of my depth on the backend and the platform underneath it.
Languages
Java 8, 11, 17 and 21, SQL and PL/SQL, Python, JavaScript, TypeScript, C, C++
Backend and Java EE
Spring Boot, Spring MVC, Spring Data JPA, Spring Security, Spring Cloud (Gateway, Config, Netflix), Hibernate, Helidon, Servlets, JSP, JDBC, multithreading
APIs and integration
REST, GraphQL, SOAP (JAX-WS, JAX-RS), OpenAPI and Swagger, OAuth2, JWT, SAML, API gateways, circuit breakers with Resilience4j and Hystrix
Messaging and streaming
Apache Kafka, RabbitMQ, IBM MQ, ActiveMQ, event-driven design, saga and outbox patterns, dead-letter handling, Spark Structured Streaming
Cloud
AWS (EC2, ECS, EKS, Lambda, RDS, S3, API Gateway, CloudWatch), Azure (AKS, App Service, Functions, Azure SQL), GCP (GKE, BigQuery, Pub/Sub, Cloud Run)
Containers and infrastructure
Docker, Kubernetes, OpenShift, Helm, Istio, Terraform, Ansible, Argo CD, horizontal pod autoscaling
Data
Oracle, SQL Server, PostgreSQL, MySQL, MongoDB, Cassandra, DynamoDB, Redis, Cosmos DB, query tuning and indexing, Airflow
Frontend
Angular, React, TypeScript, Redux, NgRx, RxJS, Material UI, Bootstrap, Tailwind CSS, accessible and responsive design
Delivery, quality and observability
Jenkins, GitHub Actions, GitLab CI, Azure DevOps, Maven, Gradle, JUnit, Mockito, Selenium, Cypress, JMeter, SonarQube, Prometheus, Grafana, ELK, Splunk
How I work
The engineering principles I bring to design, delivery and review.
Design for the failure case first
Every network call can time out and every message can arrive twice. I make that explicit in the design instead of finding it in production.
Make it observable
Metrics, structured logs and alerts ship with the feature, so on-call engineers can answer “what happened” in minutes.
Leave it simpler than I found it
Clear module boundaries, honest naming and tests that describe behavior make the next change cheaper.
Raise the team
I review code to teach, write the design doc before the code, and pair on the hard parts.
Have a backend that needs to scale or stop breaking?
I'm available for senior Java, full stack and cloud engineering roles. The quickest way to reach me is email.