Bishwajit Purkaystha

A Next.js-based marketplace application supported B2B business transactions and communications. This website only offered agro products. I was a part of the 4-developers team, which built the MVP of the website.

The website provided product listings and filtering, search engine, deal negotiation, timeline, and messaging. We modularized the whole project and adopted re-usable React functional components. We stored the product and user information in the Neo4j graph database.

Around 100+ sellers listed 500+ products on the website.

A new credit card statement generation UI tool.

I wrote this application single-handedly and from scratch, using React to provide a smooth user experience for different user roles. The application has many different functions, allowing users to perform various actions, such as generating, downloading, and emailing statements, managing other users, and tracking issues.

The statement generation UI is highly interactive and gives users live statistics on how the statements are generated and processed.

A React-based front-end application.

I single-handedly developed this application, which has several UI components visible to the users who have specific roles.

About a hundred internal users use this application to monitor, administer, and generate reports, covering the payment operations performed by customers.

The application also enables its admin users to regulate all the payment features in compliance with the central bank's instructions.

A set of microservices developed in Spring Boot. I emphasized data caching on the Redis server to reduce the delay for the lifetime of transactions. Before I created the caching, the system could process about a thousand transactions per second; the throughput increased by almost four times after I introduced the caching.

As a transaction would route through two or more microservices in its lifetime, we introduced a set of status codes to maintain fail-safety. We also enabled scheduling to auto-resolve the transactions from the non-terminal states. We used mainly REST APIs for the communication between any two microservices. Additionally, we used asynchronous messaging systems, such as RabbitMQ and Apache Kafka, for less sensitive communications.

A middleware application for integration with several mobile wallet providers across the country.

As part of a team, I developed this application, which connects to 5+ mobile financial providers through which the bank users can transfer money between their bank accounts and mobile wallets.

The application has a microservice architecture, and it's written in Spring Boot with an Oracle database. Each month, around a billion dollars (in the local currency) are transacted through this application.

A new credit card statement generation back-end service.

While working in a team, I developed this application to replace the existing one. The application generates, records, and maintains individual statements. The previous system processed each statement one at a time, requiring 35 to 40 hours to process a hundred thousand credit card statements.

When we introduced parallelization using RxJava in the Spring Boot framework, the result was staggering; the same number of statements could be generated in less than ten minutes. I used iText7 for actual PDF generation.

A Spring Boot MVC application with Thymeleaf that I developed single-handedly.

The application sends short URLs to the cell phones of nearly 1.5 million BRAC Bank clients on a half-yearly basis. The short URLs uniquely identify each bank client. The application can handle around ten thousand API requests per second.

An in-memory database is implemented to reduce the latency. To date, 150 million statements have been downloaded through this application.

A CRM application for iPay.

I developed this application used by 50+ employees of iPay for user verification, activation, and service. The application had two facades. The front end was developed in React with attractive UI components and the back end in Java Spring Boot around a microservices architecture.

More than 200,000 users of iPay have been verified, using this application