Ranjan Kumar Mandal

Experience

Sep 2025 – Present

Technology Stack: React, Redux, GraphQL, Java, Spring Boot, NiFi, Kafka, PostgreSQL, MongoDB, Radis, LLM, LEC, GCP, REST

May 2025 – Sep 2025

Technology Stack: React, Redux, GraphQL, Java, Spring Boot, Spring AI, Kafka, MySQL, MongoDB, Radis, LLM, AWS, REST

Worked in Commerce Solution which product lines Cashstar, Nimble, Giftcards.com with B2C, B2B, D2C business channel
Worked for new feature in promotion and order service to manage promos with PIM and catalog service to Voucherify
Worked in /v3/orders DDP service that helped respective brand’s (Like – Amazon, Walmart, Delta Airline, Rakuten, etc.)
Where millions of customers can apply their promo or vouchers on 1st or 3rd party BHN own platform
Worked in BHN Promo Assistant, an LLM based AI application from scratch, driving multi-million-dollar revenue impact

Oct 2023 – May 2025

Technology Stack: React, Redux, GraphQL, Java, Spring Boot, Kafka, Azure Sql, Cosmos DB, Radis, LLM, Azure, WCNP, REST

Worked in a new talent development and in a Walmart internal LLM based AI application development project
Worked in auto-purge feature from scratch using CRPA API
Automated system to purge all candidate information where retention period exceeds 5 years
Worked in Talent MyHiring project as a full stack developer from scratch, saving million-dollar hiring costs
Worked in Galaxy project as a frontend developer, replicating existing API consuming logic
Onboarded Galaxy app to use GraphQL APQs on web and mobile platforms, reducing load time by 25%
Supported project Porter as a cloud backend developer, integrating various CI/CD and DevOps changes
Migrated DB2 dev changes to Azure SQL and optimized services, improving app performance by 20%

Mar 2022 – Oct 2023

Technology Stack: React, Redux, RxJS, Java, Spring Boot, Hibernate, Kafka, Radis, MySQL, MongoDB, Cassandra, AWS, REST

Worked in a team of engineers with agile project development, writing high-performance full stack code with JS and Java
Reduced app load time by 75% and resolved full stack bugs, contributing to multi-million dollar profit gains
Implemented sports score feature with multi-league interaction, improving customer retention during DISH downtime
Designed and implemented Swrve rewards feature and coin logic system, increasing new customer acquisition
Participated in HLD design and REST microservices development for Sling Guide 2.0 feature
Designed and developed Spring-based security microservice used by millions on Sling and DISH Wireless
Handled CI/CD, pipeline integration, pull requests, code reviews, and performed load/stress/unit/e2e testing

Dec 2019 – Mar 2022

Technology Stack: JavaScript, TypeScript, React, Java, Spring Boot, Kafka, SQL, AWS S3, AWS SQS, JAXB, Microservices, REST

Worked under leads on developing the E-Commerce project and supported client success during festival season
Involved in bug fixes and support tasks that boosted client profits by the end of the targeted second quarter
Participated in designing and developing the ECM project, increasing global revenue by 23% in the first quarter