MY WORK
A selection of projects that showcase my expertise in building scalable systems
Domain
Engagement Type
Showing 14 of 14
Mosaics Data App
Senior Java Developer / Technical Lead• 8-person engineering team
Jan 2025 — Present
HybridFull Time
Next-generation data strategy consulting platform built on Knowledge Graphs architecture. Enables enterprise organizations to transform raw data into actionable insights through intelligent data governance, automated discovery, and strategic data architecture planning.
Responsibilities
- Technical architecture decisions
- Code review leadership
- Client stakeholder communication
- Performance optimization
Key Achievements
- Architected domain models using tactical DDD (Aggregates, Entities, Value Objects) with clear transactional boundaries; serving 10,000+ daily active users (measured via product analytics in Q1–Q2 2025).
- Eliminated anemic domain models across 5 core modules, reducing critical bugs by 45% and deployment rollbacks by 60% (Q2–Q4 2024 baseline vs Q1–Q2 2025; tracked in Jira and release dashboards).
- Implemented hexagonal architecture with Ports & Adapters, achieving 90% test coverage and reducing integration test time by 70% (JUnit 5 + Testcontainers CI).
- Designed plugin-based infrastructure enabling seamless cloud provider migrations (adapter abstraction for storage, cache, and metrics), reducing switching effort proxy by ~80%.
- Mentored 3 engineers through structured pairing and design reviews, improving team throughput by 35% over 3 sprints (Jira velocity).
- Cut P95 latency on read-heavy endpoints from 220ms to 140ms by adding Redis-backed read models, eliminating N+1 queries via fetch graphs, and indexing hot columns (observed over 4 weeks in Grafana).
- Reduced GC pauses by 35% and CPU by 18% using JFR/Async Profiler to remove hot allocations and switch to Java 21 virtual threads for IO-bound handlers where appropriate.
- Hardened production: introduced feature flags and canary deploys; MTTR decreased from 48m to 22m with OpenTelemetry tracing, structured logs, and SLO burn-rate alerts.
- Standardized schema migrations with Flyway and blue/green rollout steps; zero migration-related rollbacks across last 10 releases.
Notes
Compliance contribution included RBAC policy design, audit log retention configuration, encryption in transit (mTLS) and at rest, and service health/runbook definitions. Evidence available on request.
Tech Stack
Java 21 (Virtual Threads, Records)Spring Boot 3.x (GraalVM Native Images)Spring Cloud GatewaySpring Security 6 (OAuth2/OIDC)Spring Boot ActuatorReact 19 (TypeScript)Tailwind CSS 4shadcn/uiMariaDBRedisMinIOKubernetesPrometheusGrafanaOpenTelemetryFlywayFeature FlagsJUnit 5TestcontainersJFR / Async Profiler
Domain
Data StrategyKnowledge GraphsData GovernanceModern UI/UX DesignComponent ArchitectureSystem Observability
Compliance
GDPRSOXHIPAA
Feb 2024 — Dec 2024
OnsiteFull Time
Senior Java Consultant engaged in enterprise modernization initiatives focusing on microservices transformation and event-driven architecture implementation.
Key Achievements
- Prepared technical architecture strategies for monolith-to-microservices migration using Spring Boot, Kafka, and Elasticsearch aligned to bounded contexts (DDD).
- Developed event-driven architecture blueprints with Axon Framework, CQRS, SAGA patterns, and ELK (Elasticsearch, Logstash, Kibana) for observability.
- Created reactive microservices implementation plans with Project Reactor for high-throughput systems targeting 70% latency reduction, including backpressure and timeouts.
- Served as senior interviewer for Java/Spring/microservices/system design roles; designed rubric and calibration guidelines.
- Delivered reference services (order, payment, inventory) illustrating outbox + Debezium CDC, idempotent consumers, and DLQ handling; reduced integration flakiness in pilot by 60%.
- Wrote migration runbooks (cut-over, data backfill, smoke tests) and CI templates (contract tests, Testcontainers) to standardize service creation.
Tech Stack
Java 17+Spring Boot 3.xApache KafkaAxon FrameworkCQRSSAGAElasticsearchLogstashKibanaProject ReactorDockerKubernetesAWS/GCP/Azure (advisory)TestcontainersOpenAPI / Contract Testing
Domain
Digital Transformation
Feb 2023 — Jan 2024
HybridFull Time
Led development of resilient APIs and cloud-native IoT applications for smart building automation and industrial control systems across 48+ deployments.
Key Achievements
- Designed Spring Cloud Data Flow topologies for Kafka Streams and Spring Batch pipelines; standardized schemas and replay policies.
- Built resilient APIs with Spring Cloud Gateway, Resilience4j, and gRPC, achieving 99.9% service uptime (6-month observation; Prometheus SLOs).
- Applied Circuit Breaker and Bulkhead patterns to 6 external integrations, reducing cascade failures by 85%.
- Delivered cloud-native IoT across 48+ projects, integrating Modbus, Zigbee, Wi‑Fi, Bluetooth, and MQTT for device connectivity.
- Optimized edge hardware (Raspberry Pi, Rock Pi) for low-latency processing, improving building operations efficiency by ~40%.
- Implemented idempotent Kafka consumers with dedup stores and DLQs; message loss observed at 0 during soak tests with induced backpressure.
- Reduced telemetry ingestion latency by 32% via batching, compression, and gRPC deadlines/cancellations; stabilized P99 during peak hours.
Tech Stack
Java 11+Spring BootSpring Cloud GatewayResilience4jgRPCApache KafkaSpring Cloud Data FlowMySQLRedisDockerKubernetesMQTTRaspberry Pi/Rock PiIoT Protocols (Modbus, Zigbee, Wi‑Fi, Bluetooth)TestcontainersWireMock
Domain
IoT SystemsResilient APIsSmart Building AutomationIndustrial Control SystemsCloud Native ArchitectureReal-time Data ProcessingMicroservicesFault ToleranceDevice ManagementSensor Integration
Sep 2021 — Jan 2023
Remote
Architected a medical event tracking system capturing the patient journey from emergency response through surgery, with distributed caching and event sourcing for complete audit trails.
Key Achievements
- Facilitated clinical stakeholder workshops; translated workflows into technical capabilities and constraints for hospital integration.
- Designed HIPAA-aligned governance: RBAC, encryption at rest/in transit, audit trails with retention, and access reviews.
- Leveraged Spring Cloud Function, Azure Functions, and AWS Lambda for variable load; reduced infra costs by ~45%.
- Built hybrid caching with Redis, Hibernate L2, Caffeine, and Elasticsearch; cut DB queries by ~60% on critical workflows.
- Implemented event sourcing with snapshotting and schema evolution; improved recovery speed by ~80% for patient history rebuilds.
- Enabled sub-second search across millions of records via Elasticsearch indices and tuned queries.
- Added method-level security for high-risk operations, masked PHI in logs, and enforced immutable audit logs (append-only store with retention policies).
- Strengthened integration tests with Testcontainers (MySQL/Elasticsearch) and WireMock; reduced production regressions by 40%.
Notes
Compliance evidence (runbooks, audit logs, retention policies) available on request.
Tech Stack
Java 11+Spring BootSpring Cloud FunctionRedisHibernate 2nd Level CacheCaffeineElasticsearchMySQLAzure FunctionsAWS LambdaDockerKubernetesEvent SourcingTestcontainersWireMock
Domain
Healthcare TechnologyMedical Event TrackingPatient Journey ManagementEmergency Response SystemsSurgical Operations SupportEvent SourcingDistributed CachingServerless ArchitectureCloud FunctionsHIPAA ComplianceMedical Data GovernanceAudit Trails
Sedaye Esfahan - Advanced Telecommunication Platform
Senior Java Developer
2023 — 2023
HybridContractConcurrent
Real-time voice communication and streaming platform with advanced data processing, call routing, and performance monitoring for a provincial telecom.
Key Achievements
- Implemented SIP signaling and media processing paths (WebRTC/RTP/RTCP) supporting 1000+ concurrent calls.
- Developed streaming infrastructure for low-latency live audio/video with QoS tuning.
- Built processing pipelines for real-time analytics of call patterns and performance metrics.
- Implemented call routing algorithms and load distribution across media nodes.
- Created monitoring dashboards for jitter/packet loss and end-to-end performance.
- Designed fault-tolerant architecture achieving ~99.9% uptime for critical services.
- Improved call quality by tuning jitter buffers and enabling ICE/STUN/TURN for NAT traversal; reduced call setup failures by ~30%.
Notes
Short-term contract executed alongside MPJ (no schedule conflict).
Tech Stack
JavaSpring BootWebRTCSIPRTP/RTCPApache KafkaRedisPostgreSQLAsteriskFFmpegWebSocketReal-time AnalyticsLoad BalancingPrometheus/Grafana
Domain
Voice Communication SystemsReal-time StreamingTelecommunicationsData ProcessingMedia ProcessingCall RoutingPerformance AnalyticsEnterprise Systems
Sep 2020 — May 2021
Remote
Strengthened authentication/authorization and expanded testing for blockchain-enabled LMS features; improved overall reliability and security posture.
Key Achievements
- Implemented OAuth2/OIDC with Keycloak, RBAC, method-level security, social login, and PKCE for certificate endpoints and educational data.
- Increased test coverage by ~60% using JUnit 5, Mockito, AssertJ, Rest Assured, and Testcontainers.
- Drove security-focused refactoring with SonarQube/SonarLint and pair programming; eliminated critical findings.
- Added security monitoring and audit logging for auth flows, certificate issuance, and sensitive data access.
- Tightened API security: resource server JWT validation (iss/aud/exp), token lifetimes aligned to risk, and refresh token rotation with reuse detection.
- Introduced SAST/DAST in CI and automated dependency updates; reduced high-risk vulnerabilities to zero outstanding.
Tech Stack
Java 11+Spring BootSpring SecurityOAuth2/OIDCKeycloakRBACPKCEJUnit 5MockitoAssertJRest AssuredTestcontainersSonarQubeAudit LoggingOWASP Dependency Check
Domain
Application SecurityBlockchain SecurityOAuth2 AuthenticationRole-Based Access Control (RBAC)Social Login IntegrationPKCE (Proof Key for Code Exchange)Comprehensive TestingTest-Driven DevelopmentCode Quality AssuranceSecurity RefactoringEdTech ComplianceCryptographic Security
2021 — 2021
OnsiteProject
Backend services for a learning management platform supporting enrollment, course management, and online learning features.
Key Achievements
- Delivered backend services for student management and enrollment within an 8‑week window (Java, Spring Boot).
- Implemented data persistence for educational content and user management with Spring Data JPA.
- Collaborated closely with product owner to define acceptance criteria and ensure timely delivery.
- Fixed N+1 issues on enrollment endpoints using fetch joins and added indexes on (student_id, course_id), reducing DB time by ~40%.
Tech Stack
JavaKotlinSpring BootSpring Data JPAOracle DatabaseREST APIsMavenJUnit 5
Domain
Backend DevelopmentREST APIsDatabase IntegrationEducation TechnologySpring Boot ApplicationsWeb Services
Oct 2019 — Aug 2020
Remote
Integrated a blockchain-based certificate generation system into an existing LMS, enabling tamper‑evident credentials and global verification.
Key Achievements
- Developed Spring microservices to issue tamper-evident digital credentials upon course completion.
- Integrated smart contracts for immutable certificate storage; enabled global verification flows.
- Built LMS-to-blockchain API integration, handling 50+ certificate requests per hour during peaks.
- Optimized multi-cloud deployment to support blockchain transaction throughput and certificate generation.
- Established monitoring with Prometheus/Grafana and Elasticsearch for issuance metrics and performance.
- Improved DB performance (JPQL tuning, Hibernate statistics), reducing certificate generation time by ~40%.
- Implemented retries and rate limiting on Web3 calls; added background queues for on-chain confirmation with idempotent callbacks.
Tech Stack
Java 11+Spring BootSpring SecurityEthereum/Web3Smart ContractsMySQLReactDockerGCP VMsPrometheusGrafanaElasticsearchREST APIsJUnit 5MockitoTestcontainers
Domain
EdTechBlockchain TechnologyDigital CertificationsSmart ContractsDistributed LedgerLMS IntegrationCloud InfrastructureCertificate VerificationCryptographic Security
2020 — 2020
RemoteContract
Backend for a patent management and intellectual property platform supporting research, documentation, and workflow management.
Key Achievements
- Delivered core backend components for patent research and documentation workflows.
- Implemented storage and search capabilities for patent and IP documentation.
- Collaborated with attorneys and researchers to translate requirements into technical solutions.
- Added PostgreSQL full-text search (tsvector/tsquery) for document lookup and batch processing for bulk imports.
Tech Stack
JavaSpring BootPostgreSQLREST APIsDocument ProcessingSearch SystemsMavenGitFlyway
Domain
Patent ManagementLegal TechnologyR&D Software PlatformsBackend DevelopmentDocument ManagementIntellectual Property Systems
2019 — 2019
OnsiteProject
Backend development for messaging and communication systems with a focus on concurrency and automated testing.
Key Achievements
- Built multi-threaded Java services using Akka for concurrent message processing.
- Implemented unit tests with JUnit and explored performance testing with JMeter.
- Participated in CI/CD and containerization workflows for backend deployments.
- Applied Akka supervision strategies and bounded mailboxes to stabilize throughput; reduced tail latency under load by ~25% in tests.
Notes
Short-term project. Timing may overlap with other engagements.
Tech Stack
JavaAkkaSpring BootJUnitJMeterDockerMaven
Domain
Backend DevelopmentMulti-threadingConcurrent ProgrammingUnit TestingJava ApplicationsMessage Processing
2018 — 2019
OnsiteFull Time
Refactored and modularized monolithic applications into independent services; delivered new REST APIs and database modules to improve maintainability.
Key Achievements
- Extracted REST API modules from a monolith over ~9 months; reduced code coupling and improved change safety.
- Implemented data access layers and service components to isolate business logic and enable reuse.
- Contributed to process improvements that increased team throughput by ~33% (internal tracking).
- Introduced CI builds with unit/integration test stages; stabilized deployment pipeline and reduced manual release steps.
Tech Stack
JavaSpring BootSpring Data JPAREST APIsJUnitMavenCI/CD
Domain
Backend DevelopmentApplication RefactoringREST APIsDatabase DesignEnterprise ApplicationsSystem Maintenance
2017 — 2018
HybridContract
Launched and administered Moodle LMS for an educational institute, including configuration, training, and ongoing support.
Key Achievements
- Deployed and configured Moodle LMS, enabling online learning and assessment.
- Set up user management, course structures, and grading workflows.
- Trained faculty and provided documentation and ongoing support.
- Automated backups and applied security hardening (HTTPS, strong passwords, role permissions review).
Tech Stack
Moodle LMSPHPMySQLApache HTTP ServerLinuxTechnical Documentation
Domain
Education TechnologyLearning Management SystemsMoodle AdministrationOnline LearningEducational TrainingSystem Implementation
2016 — 2017
OnsiteContract
Company website and basic CRM to fill operational gaps in the main application, improving workflow efficiency and customer management.
Key Achievements
- Launched company website to establish online presence and showcase services.
- Built a basic CRM to capture and track customer interactions and projects.
- Implemented forms and data models that streamlined data entry and reporting.
- Added simple role-based access and exportable reports for management.
Tech Stack
JavaSpring MVCJSPThymeleafMySQLHTML/CSSJavaScriptBootstrapApache TomcatMavenGit
Domain
Web DevelopmentCRM DevelopmentBusiness ApplicationsSystem IntegrationCustomer ManagementConstruction Industry
2014 — 2015
OnsiteInternship
Internship project: web-based system to manage vehicle inventory, sales processes, and customer information.
Key Achievements
- Developed inventory and sales modules for dealership operations.
- Created simple reporting for sales tracking and inventory management.
- Implemented database schemas and UI forms for data entry.
Tech Stack
JavaJSPSpring MVCMySQLHTML/CSSJavaScriptBootstrapApache TomcatMaven
Domain
Automotive IndustryDealership ManagementInventory SystemsSales ManagementWeb DevelopmentBusiness Applications
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