Shamim Ehsan, Developer in Duluth, MN, United States
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Shamim Ehsan

Verified Expert  in Engineering

Software Developer

Duluth, MN, United States
Toptal Member Since
June 2, 2020

Engaged with coding since 2013, Shamim started his professional journey in 2016. His main expertise in the IT industry is Java Spring Boot. However, he also has professional experience with C# and JavaScript. He has hands-on work experience with two fintech solutions with an aggregated daily transaction amount on a scale of billions. Moreover, he has a solid background in algorithms and data structures and know-how in education achieved during a teaching assistantship at his university.


Peak Power Inc.
Java, Spring Boot, Amazon Web Services (AWS), Docker, REST APIs, GitHub Actions...
Leading Logistics Support Company
React, Kubernetes, CircleCI, PostgreSQL, Spring Boot, Java
Kona Software Lab, Ltd.
React, Spring, Gradle, RabbitMQ, Redis, Oracle, Microservices, Spring Boot, Java




Preferred Environment

Jira, IntelliJ IDEA

The most amazing...

...thing I've developed is a highly available payment gateway for a leading financial service in Bangladesh capable of handling very large requests daily.

Work Experience

Full-stack Developer for Energy Startup

2021 - 2021
Peak Power Inc.
  • Converted their legacy PHP services into Java microservices.
  • Implemented customer portal back end with Express.js.
  • Changed manual actions to the automatic scheduler using AWS SQS.
Technologies: Java, Spring Boot, Amazon Web Services (AWS), Docker, REST APIs, GitHub Actions, RESTful Development

Java Developer

2020 - 2020
Leading Logistics Support Company
  • Implemented microservice endpoints for the client to build their integration platform.
  • Built the admin portal using React hooks from scratch.
  • Extracted useful information from large XML requests into JSON using a MapStruct library and vice versa.
  • Converted a traditional endpoint to a reactive endpoint using a Spring reactor for better performance.
Technologies: React, Kubernetes, CircleCI, PostgreSQL, Spring Boot, Java

Software Engineer (R&D)

2018 - 2020
Kona Software Lab, Ltd.
  • Designed, implemented, and led multiple microservice components of the Laototo Lottery Game in Laos. Implemented the refund and SMS gateway services from scratch and oversaw the reward management service.
  • Developed the back end of a payment gateway service for Nagad, one of the country's largest mobile financial service providers.
  • Helped the front-end team by fixing bugs and implemented new pages in the customer website for the lottery game.
  • Singlehandedly transformed a gigantic codebase from Spring Boot 1.4 to Spring Boot 2.0. The microservice ecosystem has 30+ independent services.
  • Worked directly in the user management service at Kona Card, an emerging fintech solution in South Korea.
Technologies: React, Spring, Gradle, RabbitMQ, Redis, Oracle, Microservices, Spring Boot, Java

Software Engineer

2017 - 2018
Enosis Solutions
  • Converted an existing Android and iOS app to a hybrid app in Xamarin, a C#-based cross-platform mobile framework following the MVVM pattern in MVVMCross.
  • Built a POC project in Xamarin, which helps the company confirm a deal with the client using FreshMVVM.
  • Built an Android app for the QA team to test a third-party SDK.
Technologies: Xamarin, C#

Full-stack Developer

2016 - 2017
Backpack, Inc.
  • Worked in the early stage of the company and converted UX design to pixel-perfect React components.
  • Implemented a notification service for both front and back end, on the website.
  • Created an efficient job scheduler for adding a large number of promotion coupons into the system.
Technologies: Java, Node.js, JavaScript, React

Teaching Assistant

2016 - 2016
Shahjalal University of Science and Technology
  • Worked as a teaching assistant for course material including structured programming languages, data structures, and algorithms.
  • Assisted the course teacher in lab classes and prepared lab exam questions.
  • Evaluated theory and lab exam sheets for the students.
Technologies: Algorithms, Data Structures, C++


Nagad is a post office mobile financial service in Bangladesh. It has a huge number of active users thanks to the massive population of Bangladesh. I implemented a secure payment gateway, so users can send and receive money, and recharge mobile phone balance.


A fintech solution in South Korea. They provide prepaid cards and a mobile application with all kinds of functionalities of a physical card. EMV standards are followed and the project uses a microservice architecture. I was the back-end developer.

Aprio Board Meeting App

Aprio is a board meeting app where users can schedule, manage meetings, and track the progress of current tasks. I was the main developer for converting existing Android and iOS apps to a uniformed Xamarin app.

Lao Toto Lottery Game

A joint collaboration between Lao Toto from Laos and Kona I. from South Korea. This project will be a classic 5/45 lottery game. I contributed to design decisions and API designs and oversaw user management, reward management, SMS gateway service, and refund management modules.


Backpack, Inc. is a YC-backed eCommerce startup operating in Bangladesh. Users can order from popular US sites that don't ship products to Bangladesh, and Backpack brings them from the USA. I have implemented user and product pages from UX design and was part of building the notification service.
2021 - 2022

Master's Degree in Computer Science

University of Minnesota - Duluth, MN, USA

2013 - 2017

Bachelor of Science Degree in Computer Science

Shahjalal University Of Science And Technology - Sylhet, Bangladesh


React, REST APIs, Node.js, Socket.IO


Gradle, RabbitMQ, Confluence, MQTT, IntelliJ IDEA, Jira, CircleCI, Jenkins


Spring Boot, Spring, Express.js, Swagger, Hibernate


REST, Microservices Architecture, Microservices, RESTful Development


Java, JavaScript, C++11, HTML, ECMAScript (ES6), C#, HTML5, CSS, Swift, C++


Linux, Android, Xamarin, Docker, Firebase, Oracle, Amazon Web Services (AWS), Google Cloud Platform (GCP), Kubernetes


Oracle SQL, MySQL, PostgreSQL, Redis, Memcached, Spring Data JPA


Competitive Programming, Mathematics, Algorithms, Data Structures, Axios, Web Security, GitHub Actions

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