Gursimranjit Singh, Developer in New Delhi, Delhi, India
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Gursimranjit Singh

Verified Expert  in Engineering

Software Architect and Full-stack Developer

New Delhi, Delhi, India
Toptal Member Since
April 5, 2022

Gursimranjit is a software engineer and AWS-certified solutions architect and developer with experience building scalable web applications, including performing project analysis, designing architecture, and conducting end testing and deployment. He is passionate about transforming business plans into high-performance working modules. Gursimranjit enjoys testing his code, following clean and best coding practices, and brainstorming ideas before implementing them into code.


Topkey, Inc.
Ruby, Ruby on Rails (RoR), APIs, PostgreSQL, Codat, Cloud66,
N.O.N. Administration LLC
Node.js, HTML5, JSON API, APIs, Amazon DynamoDB, Amazon EC2, React, Redux...
Ruby on Rails 5, Test-driven Development (TDD), Amazon Web Services (AWS)...




Preferred Environment

Ruby on Rails 5, Node.js, PostgreSQL, MongoDB, React, Amazon Web Services (AWS), Serverless Architecture, Test-driven Development (TDD), Heroku, Angular

The most amazing...

...project I've designed is a complete back-end architecture and DB schema regarding registrations, including multiple payment gateways for payments and refunds.

Work Experience

Back-end Developer

2022 - PRESENT
Topkey, Inc.
  • Integrated Unit API, a banking-as-a-service platform, to onboard customers, issue and manage credit and debit cards, and handle transactions via webhooks.
  • Integrated an end-to-end payment workflow (with ACH, cards, and more) for debit and credit cards, including auto and manual (one-time) repayments of credit accounts dues from customers.
  • Integrated Twilio APIs to process the text and data sent by customers on the client's Twilio messages by adding a Twilio webhook.
  • Handled and maintained the staging and production environments in Cloud66.
Technologies: Ruby, Ruby on Rails (RoR), APIs, PostgreSQL, Codat, Cloud66,, Ruby Gems, Redis, ActiveAdmin, Amazon Web Services (AWS), Plaid API, Unit, Twilio API, Stimulus, Firebase, Leadership, Metaprogramming, Card Payments, Algorithms, Technical Architecture, Lambda Functions, Full-stack Development, Git, Sidekiq, Performance, Scalability

Full-stack Developer

2022 - 2022
N.O.N. Administration LLC
  • Implemented the user's identity authentication workflow to validate whether the user's identity was valid or not by capturing the front and back of the identity card along with face image recognition.
  • Took decisions to set up the project's architecture, including AWS Secrets Manager for secrets, DynamoDB for the data layer, AWS S3 for object storage, and AWS EC2 for application deployment.
  • Integrated third-party APIs to validate the user's identity and stored the corresponding results in the AWS DynamoDB and AWS S3.
  • Set up the front-end and back-end applications on the EC2 server, including NGINX as a web server. I also put together domain and SSL integrations in the GoDaddy domain registrar and mapped them with the EC2 instance.
Technologies: Node.js, HTML5, JSON API, APIs, Amazon DynamoDB, Amazon EC2, React, Redux, NGINX, Express.js, WebSockets, Amazon Web Services (AWS), API Integration, Leadership, Metaprogramming, Algorithms, Technical Architecture, Full-stack Development, Git

Software Engineer

2020 - 2021
  • Handled the back-end services, including database designing and AWS architecture.
  • Integrated the recommendation engine, using AWS serverless architecture for SMBs to make the right software choice.
  • Automated basic/daily used workflows by different stakeholders to remove their dependency on reaching out to devs for their requirements so that they can do their tasks in click(s).
  • Contributed to the CircleCI pipeline to set up better development practices and testing strategies in the team.
Technologies: Ruby on Rails 5, Test-driven Development (TDD), Amazon Web Services (AWS), Serverless Architecture, AWS Lambda, Amazon S3 (AWS S3), JavaScript, React, Solr, Python 3, Docker, Amazon Elastic Container Service (Amazon ECS), Full-stack, Front-end, Back-end, Databases, Ruby on Rails (RoR), APIs, eCommerce, MERN Stack, Team Leadership, Online Ordering, Webflow, SQL, MySQL, Metaprogramming, Algorithms, Full-stack Development, Git, Amazon Simple Queue Service (SQS), Scalability

Software Engineer

2017 - 2020
Metadesign Solutions Pvt Ltd
  • Supervised and owned the responsibilities of driving modules and OKRs.
  • Experienced upgrading the legacy code to the latest tech stack by following best coding practices, keeping in mind the scope of the project's growth.
  • Took responsibility for leading a team of four, including managing the execution and timely delivery of projects and maintaining superior quality of work.
  • Developed a portal, enabling users to register to events using multiple payment gateways and used WebSockets to reflect the seat availability on the UI.
  • Used WebSockets to create two-way communication between multiple devices.
  • Developed a Chrome extension to download a certain number of videos in the background using Web Workers.
Technologies: Ruby, Ruby on Rails 5, Node.js, React, PostgreSQL, MongoDB, Amazon Web Services (AWS), Heroku, JavaScript, Redux, Full-stack, Front-end, Back-end, Databases, Ruby on Rails (RoR), APIs, TypeScript, Architecture, eCommerce, MERN Stack, Team Leadership, HTML5, Online Ordering, Webflow, Software Architecture, Webhooks, Facebook API, SQL, MySQL, Express.js, Firebase, Stripe, Leadership, Next.js, Metaprogramming, Card Payments, Algorithms, Technical Architecture, Shopify API, Lambda Functions, Full-stack Development, Git, Amazon Simple Queue Service (SQS), Sidekiq, Performance, Amazon RDS, Scalability

Event Management System

A portal for organizing events where users can register with multiple payment gateways, such as PayPal, Stripe, CCAvenue, and Braintree. The portal provides numerous features, including upgrading, downgrading, and canceling seats, which further trigger payment/refund requests.

Used WebSockets to reflect the live seat availability count on the UI and AWS for deployments and object storage.

Recommendation and Personalization Engine

An integrated recommendation engine that uses AWS services, enabling SMBs to make the right software choice. It provides recommendations to users based on their history visits, product popularity, and top category products.

I set up the complete AWS serverless architecture to obtain user interactions and train the data model, using AWS Cloudformation, AWS step functions, and AWS Lambda functions.

Chrome Extension

A Google Chrome extension is used to download videos in chunks with Web Workers in background threads and store them in Chrome storage to enable offline playing mode.

Added a feature that allows users to pause and resume the download process per their requirements.


A MERN stack-based project where the microservices connected with a third-party healthcare device feed data to our DB, and once the data is fed, the change streams are triggered and data are transmitted to the FE via web sockets.

E-signature on PDF

A web application built with React where users can upload a PDF file and create a digital signature and some modifications on it by adding text and saving it or storing it in the S3 to serve as a backup in their accounts.
2021 - 2022

Master's Degree in Software Systems

Birla Institute of Technology and Science - Pilani, Rajasthan, India

2013 - 2017

Bachelor's Degree in Computer Engineering

Guru Gobind Singh Indraprastha University - New Delhi, India

JULY 2020 - JULY 2023

AWS Certified Developer Associate


MAY 2020 - MAY 2023

AWS Certified Solutions Architect Associate



Node.js, React, REST APIs, Sidekiq, Stripe API, Twilio API, PayPal API, jQuery, Facebook API, Stripe, Shopify API, JSON API, Plaid API


Git, Solr, Amazon Elastic Container Service (Amazon ECS), Amazon Simple Notification Service (Amazon SNS), AWS Step Functions, Mongoose, NGINX, Docker Compose, RSpec, Cloud66,, Amazon Simple Queue Service (SQS)


Ruby on Rails 5, Redux, Ruby on Rails (RoR), Angular, Express.js, Next.js, Stimulus


JavaScript, Ruby, GraphQL, SQL, TypeScript, CSS, HTML5, Python, Python 3, HTML


Serverless Architecture, Test-driven Development (TDD), Metaprogramming, Database Design, Microservices


Amazon Web Services (AWS), AWS Lambda, Heroku, Docker, New Relic, Amazon EC2, Webflow, Firebase


PostgreSQL, MySQL, MongoDB, Amazon S3 (AWS S3), Databases, NoSQL, Redis, Elasticsearch, Amazon DynamoDB, JSON


WebSockets, Back-end, APIs, Architecture, Online Ordering, Software Architecture, Webhooks, Algorithms, Technical Architecture, Lambda Functions, Web Development, Online Payments, Chrome Extensions, Payment APIs, CCAvenue, Autoscaling, Agile Sprints, Full-stack, Front-end, eCommerce, MERN Stack, Team Leadership, Leadership, Card Payments, Web Project Management, Full-stack Development, Indexing, ACH, Performance, Amazon RDS, Scalability, CI/CD Pipelines, API Integration, Codat, Ruby Gems, ActiveAdmin, Unit, E-signatures

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