Looking for a job

Kostya Kazmiruk

@kostyakazmiruk

I'm a backend engineer, and the work I'm proudest of is rarely the feature - it's the thing that made the next ten features cheaper.

Ukraine

Message

At Crystalogic, I owned customer-facing email delivery handling 10k+ emails per day, aggregating data from microservices and third parties. I built the delivery layer as a reusable library.

I also designed and implemented a unified migration CLI with module discovery, and extracted more than 20 core libraries to reduce infrastructure coupling to application code. Those libraries became standard across the microservices for developers to use.

My most recent project was in the payment domain, designed for high-load and event-driven architecture. We had 10+ multi-tenant clients with 1M+ customers each for whom we processed payments and loyalty program infrastructure.

Stack
TypeScript · NestJS · DDD · Kafka · Saga · PostgreSQL· CQRS · event-driven

Looking for problems hard enough that architecture actually matters, and a team that treats them that way.

Description and impact of last project architecture and how I guaranteed durable delivery
https://www.youtube.com/watch?v=cPrW5NDsfGU

Architecture of last project DDD
https://github.com/Sairyss/domain-driven-hexagon

Here is my availability to schedule the call
https://appt.link/meet-with-kostya-kazmiruk-qNzkHVaI

Experience

Work history, roles, and key accomplishments

BackEnd Developer

Crystalogic

Dec 2025 - Aug 2026 (8 months)

Owned crucial customer-facing email delivery (10k+/day), including aggregation of data from microservices and third-parties. Designed and implemented a unified migration CLI and extracted 20+ core libraries to remove infrastructure coupling.

NestJS DDD Multi Tenant Environments Kafka CQRS Microservices Slonik PostgreSQL TypeScript

BackEnd Developer

SKELAR Liven

Aug 2025 - Oct 2025 (2 months)

Implemented Calendly webhook with scheduling/rescheduling workflows and maintained Solidgate payment webhook integration. Developed complex data transformation logic for BigQuery analytics pipeline.

NestJS GraphQL Microservices TypeORM PostgreSQL Sentry Docker GCP DigitalOcean Zod

FullStack Developer

Queldra

Mar 2025 - Jul 2025 (4 months)

Built a platform for language learners with chat and AI suggestions via WebSockets. Created a UI library for a unified design system and implemented a platform for advertising audiences and campaigns.

NestJS JWT Prisma ORM PostgreSQL Swagger WebSockets ChatGPT API Docker Hetzner Tailwind Zod Tanstack Query TanStack Router TanStack Form

Front End Developer

Finport Technologies

Oct 2023 - Oct 2024 (1 year)

Implemented page builder and grid builder that helped deliver 30+ pages. Implemented multi-step authentication and an abstract form builder for large dataset input and persistence.

Next.js React Query Tailwind Radix UI Redux TypeScript Docker

FullStack Developer

Wenda SRL

Mar 2022 - Oct 2023 (1 year 7 months)

Owned technical direction for a two-engineer team, working directly with the CTO. Built and operated CI/CD pipeline on AWS, then rebuilt it for a WebSocket architecture and added end-to-end coverage.

NodeJS tRPC Zod PostgreSQL Prisma ORM Docker EC2 AWS RDS Next.js Tailwind Cypress

FrontEnd Developer

MusicAsCode

May 2021 - Jan 2022 (8 months)

Built component-level permission handling and a song feedback/rating feature. Improved user experience in routing based on content in URL.

React JavaScript HTML CSS VirtualBox Linux

Education

Degrees, certifications, and relevant coursework

Igor Sikorsky Kyiv Polytechnic Institute

Bachelor of Science, Computer Engineering

2019 - 2023

Bachelor of Science in Computer Engineering from Igor Sikorsky Kyiv Polytechnic Institute, 2019-2023.

Kyiv Polytechnic Institute

Developer Student Club, Computer Science

2020 - 2021

Activities and societies: Directed and coordinated a JavaScript/ReactJS learning course, engaging and guiding a group of 50+ participants.

Developer Student Club at Kyiv Polytechnic Institute, 2020-2021, where I directed and coordinated a JavaScript/ReactJS learning course, engaging and guiding a group of 50+ participants.