Vijai Selvan | Java Backend Developer

About Me

I'm a backend developer who doesn’t just write code — I build recovery paths, solve real-world data issues, and think in terms of system resilience and business impact. I specialize in clean, modular Spring Boot APIs backed by MongoDB, and have front-end experience designing responsive websites with modern HTML/CSS.

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Skills

Work Experience

Associate

Cognizant

Oct 2023 – Present

Projects: 1. ELZ Flat File Recovery API - Internal Tool for Data Recovery, 2. FileNet API Migration - Secure OAuth2 Integration with Azure Active Directory, 3. NHID Rotation for PCI DSS 4.0 Compliance

Programmer Analyst

Cognizant

Sep 2022 – Oct 2023

Projects: 1. Investment Account Aggregation and ACAT Transfer, 2. Address Validation Middleware for RLOC Application Workflow, 3. CBB Lending - Post Submission Messaging Enhancement

Programmer Analyst Trainee

Cognizant

Sep 2021 – Sep 2022

Projects: 1. Application Data Reconciliation & Backend Remediation - Customer Acquisition Platform, 2. FDIC Freeze Support - Backend Ops Coordination

Frontend Developer

GMC Council

Apr 2020 – Dec 2020

Project: Designed & Developed www.gmccouncil.org - A Student-Centric Educational Platform

Role: Associate

Company: Cognizant

Domain: Banking & Financial Services

Project:

ELZ Flat File Recovery API - Internal Tool for Data Recovery

Developed a backend recovery API to manually retrieve and regenerate critical ELZ flat files lost due to a failed batch process triggered by a pod restart in a production banking environment. This tool enabled 100% data restoration based on user-provided business dates, ensuring uninterrupted downstream reporting for high-priority financial products.

Java Spring Boot MongoDB REST API JUnit Maven File I/O Jackson SLF4J Postman GitHub Copilot

Developed a Java Spring Boot REST API to extract missed records from MongoDB and regenerate ELZ flat files, enabling seamless data restoration after batch failures due to pod restarts.
Structured modular backend layers (Controller, Service, Repository, Mapper) to ensure clean separation of concerns and high maintainability.
Queried MongoDB using Spring Data and MongoTemplate with business date and cut-off time logic for accurate data selection.
Built file I/O logic to generate critical application and event flat files in ELZ format, and stored them on NAS for downstream consumption.
Used Jackson for JSON serialization/deserialization, enabling smooth data exchange between backend systems.
Built robust logging and exception handling using SLF4J, ensuring traceability and debuggability during rerun execution.
Validated end-to-end data accuracy using Postman and MongoDB Compass; leveraged GitHub Copilot for faster coding iterations.
Developed robust JUnit test suites using Mockito (including static mocking), covering success, failure, and edge cases to ensure reliability of ELZ data recovery logic.
Gained hands-on experience in building resilient backend systems focused on data recovery, fault tolerance, and operational impact mitigation.

FileNet API Migration - Secure OAuth2 Integration with Azure AD

Enabled secure, cloud-compliant document upload workflows for a US-based banking client by migrating legacy FileNet API integrations to a modern, containerized FNCMS platform. Supported uninterrupted processing of high-stakes operations like ACATS and Legacy Apply during a strategic backend infrastructure decommissioning effort.

Java Spring Boot REST API OAuth2 Azure AD JSON Token-Based Auth Exception Handling Configuration Management

Ensured business continuity for investment account transfers and customer onboarding by replacing the legacy VM-based FileNet integration with a resilient, cloud-native REST API workflow.
Strengthened regulatory audit compliance by logging token-based authorization, request/response cycles, and error events tied to customer documents across lines of business.
Reduced operational risk and manual remediation efforts by enabling automated authentication and secure document ingestion aligned with OAuth2 Client Credentials flow using Azure AD.
Modernized a legacy hardcoded credential system by shifting to dynamic bearer token authorization using OAuth2, aligning with bank-wide security modernization mandates.
Supported enterprise-wide cloud migration and decommissioning roadmap by modernizing a critical component used across wealth management and business banking platforms.
Prevented service disruptions and legacy system failures by validating new token-driven upload flows across Dev, Test, and Production - prior to the retirement of older APIs.
Collaborated cross-functionally with EDM-FileNet and ACATS teams to coordinate rollout timelines, resolve integration blockers, and finalize multi-environment configurations.
Delivered a production-grade backend enhancement that reduced infrastructure dependencies, enhanced scalability, and aligned with the bank's long-term digital transformation goals.

NHID Rotation for PCI 4.0 Compliance - Secure Credential Management

As part of a compliance initiative in the banking domain, I enhanced credential security by migrating NHID database credentials from encrypted codebase values to a secure, dynamic retrieval system using HashiCorp Vault. This aligned with PCI DSS 4.0 standards and supported weekly reporting extracts. I collaborated with infrastructure and IAM teams for credential rotation and verified stable post-change application behavior.

PCI DSS 4.0 HashiCorp Vault Secrets Access Control Secure Coding Compliance

Enabled PCI 4.0 compliance by replacing static, encrypted NHID credentials with Vault-managed secrets, enhancing security and auditability.
Collaborated with ISS IAM Lifecycle & Controls team to perform live credential rotation through secure screen-sharing sessions, ensuring proper access control procedures.
Refactored configuration and authentication logic to dynamically fetch secrets from HashiCorp Vault, eliminating hardcoded credentials from the application.
Verified end-to-end functionality of weekly banking extract reports post-rotation, ensuring uninterrupted data delivery and operational continuity.
Resolved credential management incident, coordinating with TO/SMEs and infrastructure teams to meet audit-readiness goals and prevent compliance risks.

Role: Programmer Analyst

Company: Cognizant

Domain: Banking & Financial Services

Project:

Investment Account Aggregation & ACAT Transfer

This project focused on securely retrieving customer investment account data from internal systems to support ACAT eligibility checks. While the broader ecosystem included services like external aggregation (Yodlee) and document virus scanning (MetaDefender), my contribution centered on secure data integration and compliance-level auditing of internal APIs

Java Spring Boot REST API Basic Auth DTO Jenkins Logging Compliance

Developed and integrated secure RESTful services to fetch investment account data from internal systems, forming the backend foundation for asset transfer eligibility within ACAT (Automated Customer Account Transfer) workflows.
Implemented business rule-driven filtering logic to evaluate account eligibility using key attributes such as product codes, ownership structure, and account status, aligning with regulatory and business mandates.
Secured inter-service communication using Basic Authentication, dynamic credential management, and correlation ID tagging to ensure traceable and auditable API interactions across distributed systems.
Enabled compliance-grade auditing by capturing structured request/response logs and transaction metadata, supporting transparency, root-cause analysis, and adherence to financial regulations.
Improved backend reliability by implementing robust exception handling and graceful degradation logic to manage service failures without disrupting the transfer process.
Designed loosely coupled service interfaces to promote reusability, flexibility, and adherence to enterprise-wide architectural standards in multi-team environments.
Created reusable and well-structured data models (DTOs) for request/response payloads, enabling clean API communication and seamless data transformation between service layers.
Collaborated within the internal account aggregation layer of a broader ACAT system, contributing to a workflow that interfaced with document scanning (MetaDefender), external aggregation (Yodlee), and firm validation (NSCC) for full-process continuity.
Improved operational accuracy and customer experience by ensuring only eligible accounts were surfaced during transfer requests, reducing errors and manual interventions in high-volume transaction flows.
Delivered production-ready backend modules in a regulated financial environment, demonstrating expertise in secure integration, audit-focused development, and large-scale service integration in wealth management platforms.

Address Validation Middleware for RLOC Application Workflow

Developed as part of a customer acquisition platform within the Reserve Line of Credit (RLOC) application flow for a leading US-based bank to validate and standardize addresses before account creation. Helped strengthen data quality and regulatory compliance in the RLOC application lifecycle, contributing to faster onboarding and fewer downstream exceptions.

Java Spring Framework REST API AES Encryption SSL/TLS Jackson Jenkins SLF4J Jira

Designed & implemented backend services using Java and the Spring Framework to validate customer addresses via external APIs, significantly reducing failed deliveries and manual corrections.
Served as a middleware layer between upstream onboarding systems and downstream decision engines, ensuring validated address data flowed reliably through the customer acquisition process.
Configured and wired Spring beans for REST clients, SAO components and credential utilities using dependency injection, promoting clean separation and maintainability.
Integrated AES encryption and SSL/TLS protocols as per the bank’s enterprise security standards to securely invoke third-party validation APIs and ensure compliant credential handling.
Processed and interpreted validation responses to perform internal checks (e.g., PO Box, postal code match, service-down indicators), driving downstream decisions based on address quality.
Implemented Jackson-based data mappers to parse and normalize JSON/XML address validation responses, ensuring consistent data transformation across Dev, IT, UAT, and Prod environments.
Applied business rules to scrub, standardize, and enrich address data before further processing or storage.
Handled exceptions and service outages with Spring-managed error flows and custom exception classes, improving system resilience and reliability.
Instrumented logging & auditing with SLF4J and centralized audit tables, improving traceability and accelerating root cause analysis.
Collaborated with the DevOps team managing Jenkins-based CI/CD pipelines, ensuring successful deployments by externalizing environment-specific configurations using Spring properties, accelerating release cycles and minimizing environment-specific defects.

CBB Lending - Post-Submission Messaging Enhancement for CLL Applications

Improved the post-submission user experience for Consumer Line of Credit (CLL) applications by introducing dynamic messaging logic to handle “store-and-forward” scenarios-where backend systems could not immediately return a decision. The initiative ensured regulatory compliance, reduced re-submissions, and enhanced communication clarity across digital and assisted channels.

Java Spring MVC UI/UX HTML JSP CAT Risk Governance Conditional Rendering i18n

Redesigned post-submission workflows using Java and Spring MVC to detect backend processing gaps (e.g., missing ACAPS IDs) and deliver context-aware user messages during “store-and-forward” decisioning scenarios.
Developed tailored user communication logic across DIY and banker-assisted channels, leveraging JSP, HTML, and configuration-based messaging to ensure clarity during technical delays or backend review holds.
Integrated backend status flags via JavaBeans and conditional logic, enabling dynamic UI rendering that reflected real-time application state and improved customer guidance post-submission.
Standardized messaging behaviour across products and channels, externalizing content and labels using properties files and modular content templates for maintainability, messaging consistency and future scalability.
Aligned with enterprise compliance standards by securing approvals from UX, Risk, and Change Advisory teams, ensuring audit-ready messaging and process transparency.
Reduced re-submission attempts and call center escalations by proactively informing users of backend status, eliminating confusion during delayed decisioning scenarios.
Enhanced code maintainability and modularity by decoupling presentation logic from backend workflows, applying architecture best practices like centralized configuration and clean separation of UI content from backend logic.

Role: Programmer Analyst Trainee

Company: Cognizant

Domain: Banking & Financial Services

Project:

Application Data Reconciliation & Backend Remediation

Contributed to a project focused on improving backend reliability and customer onboarding experience by investigating application submission failures, remediating data flow issues, and proactively reducing future lost applications for a major banking client.

Java Spring Boot Splunk Jenkins Python Jira Debugging Quantum Metrics

Investigated backend submission issues by analyzing API interactions with external systems responsible for customer verification, eligibility checks, and automated decision-making.
Utilized tools like Splunk, internal log viewers, and state machine flow diagrams to debug backend workflows, identify logic errors, and trace application lifecycle failures.
Analyzed weekly application data extracts generated by automated Python scripts via Jenkins, ensuring data accuracy across customer onboarding flows.
Collaborated with product and engineering teams to raise and triage Jira tickets, documenting issue patterns, root causes, and fix validations.
Extracted and structured customer application data from production databases to support the resolution of failed submissions and enable customer outreach.
Investigated incomplete or incorrect data flows by inspecting backend system transitions and reviewing request/response payloads from integrated APIs.
Worked with cloned backend repositories and system logs to support debugging of business rule logic, submission paths, and application state errors.
Used Quantum Metrics to correlate customer interactions on the UI with backend API behaviour, identifying inconsistencies in full-stack workflows.
Participated in monthly metrics reporting, tracking recurring backend issues and prioritizing them based on frequency and business impact.
Reviewed data discrepancies in extract files, compliance-triggered errors, and email communication mismatches using internal tooling, ensuring end-to-end data consistency.

FDIC Freeze Support - Backend Ops Coordination

Contributed to regulatory readiness by coordinating activities around the annual FDIC Change Freeze in the UAT environment. Ensured the application displayed a controlled placeholder ("Gone Fishing") page by triggering infrastructure-level changes via NOC team coordination. Maintained timeline adherence, access control, and validated environment state before and after the freeze to support compliance, risk mitigation, and auditability.

Banking Infrastructure Routing BIG-IP F5 ServiceNow Compliance Governance

Created ServiceNow Incidents and CTASKs to initiate freeze-related infrastructure actions in UAT, adhering to FDIC-mandated change control procedures.
Coordinated with the Network Operations Center (NOC) to enable the BIG-IP pool on port 443 to route traffic to the “Gone Fishing” maintenance page, and disabled standard app pools during the freeze.
Verified post-change application behavior by working with QA/testing teams to validate visibility of the placeholder page during freeze and restore normal functionality afterward.
Ensured timely execution and rollback of freeze activities by tracking operational timelines and maintaining communication across infra and test teams.
Contributed to audit-readiness and change traceability through precise incident documentation, freeze window compliance, and rollback validation.

Role: Frontend Developer

Company: GMC Council

Domain: Education & Student Engagement

Project:

Designed & Developed www.gmccouncil.org

Delivered a fully responsive, mobile-friendly website for Great Minds Competency Council - enriched with joyful animations, playful icons, and education-themed illustrations to reflect the spirit of learning and student engagement.

HTML5 CSS3 Bootstrap JavaScript UI/UX Responsive Design Performance

Independently planned, designed, and developed the council's official website using HTML5, CSS3, Bootstrap, and JavaScript - now live and serving as the organization’s primary digital presence.
Transformed raw ideas into a live product, designing intuitive layouts, clean navigation, and accessible content that improved information flow and visitor engagement by 70% (based on stakeholder feedback).
Infused the website with vibrant animations, playful icons, and student-friendly illustrations, thoughtfully pairing colour themes, typography, and visual elements to reflect the organization’s personality and create a joyful, education-focused user experience.
Integrated downloadable study materials, brochures, and dynamic content sections, helping students and parents easily access academic resources.
Delivered a visually polished and fast-loading site, following front-end performance best practices — image optimization, semantic markup, and modular CSS - ensuring excellent UX and SEO readiness.
Handled full project lifecycle from gathering requirements and prototyping UI/UX to final deployment - demonstrating end-to-end ownership and delivery capability.
Delivered a professional, easy-to-maintain website with well-documented code, allowing non-technical users to manage content updates with minimal support.
Received personal recognition from the council leadership for creating a digital platform that transformed manual student engagement into an accessible, modern web experience.

Contact Me

Let’s connect! I’m open to backend or full-stack roles and collaboration.

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