Backend & Frameworks
Primary stack across nine-plus years of enterprise Java delivery — from Spring MVC-era monoliths through Spring Boot microservices on Java 21.
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Senior Java Engineering Leader · 17+ years
Sanjay Singh Bhandari
Enterprise Java platforms — from architecture to production.
I design and build the backend systems organizations depend on — authentication that holds up across every client deployment, trading systems engineered not to go down, and financial systems underneath it all. 17+ years doing that in Java, now extending the same discipline into AI-powered products.
17+
Years of experience
16
Microservices architected (Exchange Platform)
99.9%
Production uptime (Exchange Platform)
5–7
Developers led (last ~5 years at Opal)
Impact Dashboard
Why this is worth 20 seconds of your time.
A CTO-level summary: verified scale, domains, technology, and outcomes — no filler, no unverified claims.
Engineering Impact
17+
Years of experience
16
Microservices in one production platform
99.9%
Uptime, Enterprise Exchange Platform
5–7
Developers led (last ~5 years at Opal)
<50ms
P95 latency, Beckn Protocol adapter
30%
MTTR reduction, InterGlobe production support
Core Engineering Domains
Distributed Systems & Data
Event-driven and data-layer technologies used in production trading and platform systems, including the Enterprise Exchange Platform.
Learn more →Security & Identity
I led the design and rollout of an OAuth2-based authentication and authorization system across multiple production client deployments.
Learn more →Cloud & Delivery
CI/CD strategy, containerization, and cloud deployment ownership — defining pipelines rather than just using them.
Learn more →AI Engineering
Applying LLM-based tooling and retrieval-augmented generation to real, shipped resume/hiring products — see the AI Engineering page for specifics.
Learn more →Leadership Practice
During the last five years at Opal BPM, I mentored a team of 5–7 developers and drove architecture/code-review standards — see the Leadership page for the practices behind each of these.
Learn more →Architecture & Systems Design
4 cross-cutting architectural themes drawn directly from the case studies — service decomposition, event-driven consistency, identity/trust boundaries, and individual ownership inside team-scale systems.
Learn more →Technology Ecosystem
Languages
JavaPython
Frameworks & Libraries
Spring BootSpring MVCFastAPIFlaskReactExtJSStreamlitREST APIs
Cloud & Infrastructure
AWS
Messaging & Async
KafkaCelery
Databases
PostgreSQLRedisOracleMySQLSQLite
Containers & Orchestration
DockerKubernetes
CI/CD & Build
JenkinsCI/CDMavenGradle
Security & Identity
OAuth2JWTSpring Security
AI Engineering
LangChainRAGPrompt Engineering
Payments
StripeRazorpay
Engineering Strengths
Enterprise Architecture
I architected two production platforms from the ground up at Opal BPM: the 16-microservice Enterprise Exchange Platform and the company's core Artwork Management Platform.
See the case study →Distributed & Event-Driven Systems
I designed the Kafka-based order-to-settlement event flow behind a multi-tenant trading platform running in production at 99.9% uptime, with notification delivery under 100ms.
See the case study →Authentication & Identity
I led the design and rollout of a standardized OAuth2 authentication and authorization model across multiple independent client deployments.
See the case study →Protocol Compliance & Integration
I built an RFC 1.2.0-compliant Beckn adapter ("WRI Connector") integrating 5+ identity-verification providers behind one interface, at sub-50ms P95 latency.
See the case study →Production Support
I took direct ownership of production issue triage for InterGlobe's financial systems, reducing mean time to resolution by 30%.
See the case study →Technical Leadership
I joined Opal BPM as a Senior Java Developer and progressed into Lead Java Developer; during the last five years of my nearly 10-year tenure, I mentored a team of 5–7 developers and set code-quality and system-design standards.
See the case study →Career Snapshot
- Most recent role
- Senior → Lead Java Developer, Opal BPM (Sep 2015 – Apr 2025)
- Total Experience
- 17+ years
- Industries
- Enterprise SaaS (Retail), Trading & Marketplace Platforms, Aviation & Financial Systems
- Enterprise delivery
- Multiple client deployments (Opal BPM)
- Technical leadership
- 5–7 developers led (last ~5 years at Opal)
- Based in
- New Delhi, India
Selected Highlights
Engineering Case Studies
Systems designed under real constraints.
Architecture decisions, tradeoffs accepted, and individual ownership — not a feature list.
ProductionOpal BPM India Pvt Ltd
Enterprise Exchange Platform
A 16-microservice trading platform matching buyers and sellers across multi-tenant e-waste categories, run at 99.9% uptime.
Java 21Spring Boot 3.4.13MicroservicesPostgreSQLKafka
Read case studyProductionOpal BPM India Pvt Ltd
Beckn Protocol Verification Adapter
An RFC 1.2.0-compliant Beckn adapter ("WRI Connector") for identity verification across multiple providers, with sub-50ms P95 latency.
Python 3.12+FastAPIPostgreSQLCeleryDocker
Read case studyProductionOpal BPM India Pvt Ltd
OAuth2 Authentication Platform
A standardized OAuth2 authentication and authorization system rolled out across multiple client deployments of Opal's platform.
JavaSpring BootSpring SecurityOAuth2JWT
Read case studyLeadership
Leadership shown through practice, not adjectives.
Team Leadership
During the last five years of my Opal BPM tenure, I provided technical leadership to a team of 5–7 developers after progressing from Senior Java Developer into Lead Java Developer.
Opal BPM India Pvt Ltd — technical leadership of 5–7 developers, last ~5 years of Sep 2015–Apr 2025 tenure.
See it applied in a case study →Mentoring
I established code-quality and system-design practices for the team as it scaled, rather than relying on ad hoc review.
Architecture Reviews
I owned the architectural decisions behind the Enterprise Exchange Platform's 16-service decomposition and the Beckn Protocol Verification Adapter's state-machine design — decisions made and defended, not just implemented from a spec.
See it applied in a case study →AI Engineering