Senior Backend Developer • Distributed Systems & Cloud

Hi, I am Sumit Ujjwal

Senior Backend Developer

Building reliable backend systems, optimising MySQL databases, and keeping production software running on AWS. Specialised in .NET C#, Python, SQL performance, and REST APIs with a focus on maintainable Clean Architecture and high operational reliability.

View Engineering Work

PRODUCTION SYSTEMS ARCHITECTURE

Distributed Backend Systems • AWS Ecosystem

AWS US-EAST-1 HEALTHY
< 15ms p99 Latency
99.98% Production SLA
9 Services Microservices
CORE RUNTIME
.NET C# • ASP.NET Core • Python CQRS MediatR
DATA & CACHE
MySQL 8.0 RDS • Redis • Liquibase Index Optimized
CLOUD & DEVOPS
AWS EC2 • ALB • ASG • Nginx • Linux Zero-Downtime
.NET C# MySQL Redis AWS Clean Architecture REST APIs
About

Engineering Focus & Architecture

I'm a Senior Backend Developer at BigYellowFish Technologies, working on the backend systems that power the BigYellow platform. My work involves building APIs, working with databases (SQL), integrating services, and making sure things continue to work as expected in production.

I enjoy the problem-solving side of backend engineering — understanding why something isn't working, figuring out where things can be improved, and finding practical solutions without making systems unnecessarily complicated. Whether it's debugging an issue, improving a slow query, or working on a new feature, I like understanding the problem before jumping into a solution.

Over time, I've come to appreciate that good backend engineering is about more than writing code. It's about making thoughtful decisions, keeping systems maintainable, and considering what happens after a feature goes live. That's the approach I try to bring to my work every day.

Backend Architecture

.NET C#, ASP.NET Core, Python, Clean Architecture, CQRS with MediatR, and Result-pattern error handling.

Database Engineering

MySQL, execution plan analysis, B-Tree composite indexing, Liquibase migrations, and Redis caching.

AWS Cloud Infrastructure

EC2, RDS for MySQL, ALB, Auto Scaling Groups, S3, CodePipeline, CodeDeploy, and Systems Manager.

Production Operations

Linux administration, Nginx reverse proxies, CloudWatch metric filters & alarms, and incident investigation.

Experience

Professional Timeline

Senior Backend Developer

BigYellowFish Technologies Pvt. Ltd.

Oct 2026 – Present Current Role

Promoted to Senior Backend Developer in October 2026. Leading backend engineering efforts focused on system reliability, production incident troubleshooting, MySQL/RDS database performance and upgrades, cloud infrastructure maintainability, and deployment automation across the BigYellow platform microservices.

API & Application Development

  • Direct backend service maintainability and engineering decisions across .NET Core and Python microservices, emphasizing Clean Architecture and CQRS patterns.
  • Drive design of resilient API contracts, distributed transaction safety, and Redis caching strategies to safeguard high-concurrency throughput.
  • Review engineering pull requests for architectural soundness, thread safety, Result-pattern error handling, and performance standards.

Database Engineering

  • Plan and execute MySQL / Amazon RDS engine version upgrades and parameter group tuning with zero unplanned service disruption.
  • Lead advanced database performance diagnostics, connection pool capacity planning, and mitigation of query contention under heavy enterprise traffic.
  • Enforce structured Liquibase schema migration workflows, multi-tenant safety standards, and robust rollback strategies.

AWS Infrastructure & Production Operations

  • Configure and optimize Auto Scaling Group lifecycle hooks, automated target tracking policies, and Application Load Balancer health checks.
  • Refine CI/CD pipeline automation across AWS CodePipeline and CodeDeploy for deployment consistency, automated rollbacks, and fast recovery.
  • Lead production incident investigations, root-cause analyses (RCA), and implement preventive operational improvements across Linux and CloudWatch alarms.
C# / .NET ASP.NET Core Clean Architecture MySQL / RDS Upgrades Redis AWS Auto Scaling CI/CD Automation Nginx Linux CloudWatch

Backend Developer

BigYellowFish Technologies Pvt. Ltd.

Sep 2023 – Sep 2026

Built and maintained core backend APIs, database solutions, scheduled background jobs, and cloud integrations for the BigYellow enterprise platform. Developed modular features across user management, engagement mechanics, analytics, and wearable integrations while ensuring system uptime and operational health.

API & Application Development

  • Built and maintained REST APIs using C#, .NET, ASP.NET Core, Entity Framework Core, and LINQ following maintainable architecture principles.
  • Developed Python services and automation tools, integrated external third-party APIs and wearable platforms, and implemented core backend business logic.
  • Implemented Quartz.NET scheduled background jobs, asynchronous processing pipelines, notification workflows, and Firebase Admin SDK integrations.
  • Contributed feature development across user management, analytics, management broadcasts, nudge notifications, wearable integrations, Action Management, XP levels, leaderboards, and point-based features.

Database Engineering

  • Designed and managed MySQL schemas, wrote optimized SQL queries, and authored index strategies for multi-tenant enterprise datasets.
  • Conducted query execution plan analyses (EXPLAIN) to troubleshoot and eliminate slow query bottlenecks.
  • Executed database migrations and schema changes across development, staging, and production using Liquibase.
  • Managed connection pooling, monitored RDS storage capacity growth, and resolved concurrency and connectivity issues under high workload.

AWS Infrastructure & Production Operations

  • Managed AWS cloud resources including EC2, RDS, S3, CloudWatch, Application Load Balancers, Auto Scaling Groups, and AWS WAF.
  • Built and maintained automated CI/CD deployment pipelines utilizing AWS CodeBuild, CodePipeline, and CodeDeploy.
  • Configured Nginx reverse proxies, administered Ubuntu Linux environments, and maintained SSL/TLS certificate renewals.
  • Investigated production operations, API connectivity drops, memory utilization spikes, deployment failures, and application availability using CloudWatch metrics and alarms.
C# / .NET ASP.NET Core EF Core / LINQ Python MySQL Quartz.NET AWS EC2 / RDS CodePipeline CodeDeploy Nginx Linux CloudWatch

Intensive Systems & Software Engineering

Masai School & Independent Development

2022 – 2023

Completed comprehensive full-stack and backend training program at Masai School. Built production-structured web services, solved 300+ data structures and algorithms problems, and earned Google Cloud certifications covering IAM, Compute Engine, and Cloud Functions.

.NET C# Node.js MySQL Google Cloud REST APIs Data Structures
Engineering Work

Production Case Studies

Sanitized case studies drawn from real-world backend and cloud infrastructure work. Outlining engineering problems, architectural solutions, and verified outcomes without exposing confidential business logic or private credentials.

AWS Auto Scaling and CodeDeploy lifecycle architecture diagram
AWS Infrastructure • CI/CD

Deployment Reliability and Auto Scaling Lifecycle

Production deployments depend on coordination between deployment automation, instance initialization, and load balancer health checks. Diagnosed Auto Scaling Group instance launches, reviewed lifecycle hooks and deployment sequencing, and verified that newly launched replacement instances receive the expected application version and pass health checks before serving production traffic.

AWS EC2 Auto Scaling Groups AWS CodeDeploy Application Load Balancer CloudWatch
MySQL Query execution plan comparison and composite index diagram
Database Engineering • Performance

MySQL Query Analysis and Index Optimisation

Investigated slow analytical queries and resource-heavy database operations under concurrent application traffic. Used MySQL execution-plan analysis with EXPLAIN to identify expensive joins, unindexed table scans, and data access bottlenecks. Evaluated composite indexes, improved query structure where justified by execution-plan evidence, and reduced database server resource consumption.

MySQL AWS RDS Entity Framework Core LINQ SQL EXPLAIN Analysis
Clean Architecture CQRS with MediatR and Redis cache diagram
Backend Architecture • API Design

Clean Architecture API and Background Processing

Designed maintainable backend services separating business logic from infrastructure concerns using ASP.NET Core, Clean Architecture, and CQRS patterns. Established clear boundaries between API controllers, domain logic, and persistence layers. Implemented background jobs, asynchronous notification workflows, and isolated Redis caching to ensure predictable data access and operational consistency.

C# / .NET ASP.NET Core Entity Framework Core MediatR • CQRS Redis Cache Firebase SDK
AWS CloudWatch structured logs and alerting architecture diagram
Production Operations • Reliability

Production Observability and Incident Response

Standardized production diagnostics by connecting application logs, infrastructure metrics, health checks, and deployment history. Investigated service degradation triggers including database connectivity limits and upstream proxy errors. Correlated telemetry across CloudWatch and Nginx to identify failure mechanisms, validate service recovery, and document diagnostic runbooks.

AWS CloudWatch Application Load Balancer AWS SNS Nginx Linux Diagnostic Runbooks
Technical Stack

Tools & Technologies

Categorized technologies used across backend services, database tuning, cloud architecture, and operations.

C# / .NET

ASP.NET Core

Python

Node.js

REST APIs

MediatR / CQRS

MySQL

Redis Cache

SQL Optimisation

Liquibase

AWS EC2

AWS RDS

AWS IAM / Systems Manager

AWS CloudWatch

AWS CodePipeline

Linux

Nginx

Git / Bitbucket

Docker

CI/CD Automation

Postman

Grafana

Approach

Core Engineering Principles

01

Diagnose with Evidence

Read the structured logs and inspect execution plans with EXPLAIN ANALYZE before changing code. Assumptions waste time; metrics and telemetry pinpoint root causes.

02

Design for Maintainability

Code is written once but read hundreds of times. Clear abstractions, domain boundary isolation, predictable CQRS flows, and consistent naming always outlast clever shortcuts.

03

Understand Database Internals

Understand index cardinality and access paths before tuning. Index writes have a cost; transactions must be explicit and bounded to preserve data integrity.

04

Observability is Part of Shipping

Structured logging, meaningful latency metrics, and actionable alert routes belong in the pull request with the feature, not as an afterthought during an outage.

05

Automate the Repeatable

If an operational or deployment task has been executed manually three times, it belongs in an automated CI/CD pipeline or script. Toil compounds; automation scales.

06

Protect Data Integrity

Transactions, foreign keys, idempotency keys, and versioned Liquibase migrations are non-negotiable. Data corruption is infinitely harder to resolve than a failed build.

Credentials

Certifications & Education

Full Stack Web Development

Masai School • FW22-0065

Configure Service Accounts & IAM Roles

Google Cloud • Credly Verified

Cloud Functions: 3 Ways

Google Cloud • Credly Verified

Basics of Google Cloud Compute

Google Cloud • Credly Verified
Contact

Get in Touch

Open to senior backend roles, systems architecture discussions, and technical collaborations.

GitHub

SumitUjjwal

LinkedIn

in/sumitujjwal

Email

sumitujjwal@outlook.com

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