Kirill Korolev

Backend EngineerEngineer

Open to offers · Member since 19 Sep 2026

Message

Location: Tivat, Montenegro

Desired salary: Unspecified

Work preference: Remote Only

Experience level: Mid

About

Professional summary

I am a backend software engineer with five years of commercial experience building scalable, high-performance backend systems and distributed services. My primary expertise is Python development, with a focus on reliable APIs, transactional workflows, and high-load applications.

I work extensively with FastAPI, Django, PostgreSQL, Redis, Kafka, and REST APIs. I have designed backend architectures, database schemas, integrations, and asynchronous processing pipelines while maintaining backward compatibility for existing clients and partners.

I have experience in travel technology and booking systems, where I owned critical modules processing tens of thousands of daily transactions and integrated services with major external providers. I am comfortable improving reliability, reducing latency, and supporting production systems through on-call rotations.

I also have full-stack experience, including React, TypeScript, JavaScript, HTML, and CSS. I have contributed to legacy-system migrations, internal admin tools, SEO modules, API documentation standards, and engineering processes such as code review.

My technical foundation includes algorithms, mathematics, linear algebra, analytical geometry, and C/C++. I am interested in practical applications of RAG, LLMs, SLMs, and embeddings, and I enjoy solving complex engineering problems with measurable business impact.

Tech stack & tools

Working toolkit

Experience

Career history

Fullstack Developer Korzilla

Sep 2025 – Jul 2026

Participated in the migration of a legacy PHP CMS to Python and FastAPI, moving modules incrementally while preserving backward compatibility. The migration doubled feature-delivery speed and reduced developer onboarding time from about two weeks to three or four days.

Designed REST APIs using Pydantic validation and automatic Swagger documentation in collaboration with the frontend team, improving API contract clarity. Designed normalized PostgreSQL schemas and optimized indexes, making critical queries 4–6 times faster and reducing latency on high-traffic pages.

Built admin panels and an SEO module that enabled clients to perform up to 80% of routine changes independently, reducing support workload by approximately one third. Helped establish code-review practices and standardize Swagger documentation for API development and onboarding.

Backend Engineer (Mid-level), Bookings & Inventory TravelPerk

Nov 2021 – Jul 2024

Owned a booking module processing tens of thousands of transactions per day and millions of euros in booking volume. Integrated the platform with approximately 15 external providers, including Amadeus, Sabre, HotelBeds, and Expedia Rapid.

Led the HotelBeds integration in one and a half months, adding around 250,000 properties and increasing Southern Europe coverage by approximately 30%. Built about 10 public API endpoints and a booking method while maintaining backward compatibility with roughly 200 partner integrations.

Migrated critical booking endpoints from synchronous to asynchronous processing, reducing cancellation timeout rates from about 8% to nearly zero and lowering response times from seconds to a few hundred milliseconds. Participated in on-call rotations and extracted rate limiting into a shared library adopted by three additional teams.

Junior Programmer Yandex

Sep 2020 – Oct 2021

Completed an internship on Yandex's backend team, developing and testing Python code within an established architecture. Fixed bugs and addressed technical debt under mentorship from senior engineers.

Participated in code reviews, optimized database queries, and improved internal API endpoints through production delivery. Received a positive evaluation and an invitation to join the team permanently.