m
mliubimtsev

Mikhail L

@mliubimtsev

Backend Developer Nodejs NestJS

Ukraine
English, Ukrainian
About me
Backend developer (Node.js / NestJS) with 3+ years of commercial experience. I build REST APIs, web scrapers, Telegram bots, automation scripts in plain JavaScript and integrations with third-party and payment APIs. I also handle full-cycle backend development: database design, service implementation, tests, Docker deployment. Stack: Node.js, NestJS, JavaScript, TypeScript, PostgreSQL, Redis, Docker, BullMQ, Kafka. Based in Kyiv (EET), work remotely. Send me a short description of your task and I will tell you whether I can help.... Read more

Skills

m
mliubimtsev
Mikhail L
Offline • 

See my services

Rule Based Chatbots
I will build a custom telegram bot with nodejs
From$5 / projectMore details
Data Scraping
I will do web scraping, data extraction for any website
From$30 / projectMore details

Portfolio

Work experience

Freelance

Backend Developer (Node.js / NestJS)

Freelance • Freelance

Jul 2026 - Oct 2026 • 3 mos

Service for collecting and versioning app-ads.txt files (Ad Tech). Stack: NestJS, TypeScript, PostgreSQL 16, BullMQ / Redis, undici, S3 (MinIO), Docker. Code: github.com/mliubimtsev/app-ads-worker • Reduced unnecessary traffic and database load with conditional HTTP requests (If-None-Match / If-Modified-Since) and content hash comparison: parsing and merging run only for files that have actually changed, about 0.4% of domains per day. • Designed an SCD2-lite versioning model: rows are never overwritten, the full history of transitions is written to an append-only table. • Implemented the merge via COPY ... FROM STDIN into an UNLOGGED staging table with a FULL OUTER JOIN, all within a single transaction. • Built an HTTP service on undici with per-host throttling, timeouts and a response size limit. • Tests: parser, error classification, merge; integration tests with Testcontainers. • Load test: 5 million rows processed in 6-7 minutes on a 4-core server.

Software

Backend Developer (Node.js / NestJS)

Software • Full-time

May 2025 - Jul 2026 • 1 yr 2 mos

Internal task tracker: microservices + legacy monolith. • Sped up a key endpoint 7.5x (15 s to 2 s) by moving aggregations from Node.js into PostgreSQL (about 3.3M records) and splitting the heavy endpoint. • Audited slow endpoints and SQL queries (EXPLAIN ANALYZE), eliminated N+1, moved computation logic into PostgreSQL. • Implemented Kafka producers and consumers with idempotent message processing. • Designed recursive traversal of the department hierarchy for correct display of managers. • Synchronized TypeORM / Sequelize models with the real database schema, fixed incorrectly generated migrations. • Updated Protobuf contracts for gRPC, extended DTOs and endpoints. • Jest unit and integration tests.

Confidential

Backend Developer (Node.js / NestJS)

Confidential • Full-time

Mar 2024 - Apr 2025 • 1 yr 1 mo

E-commerce platform for a sports nutrition brand (4 microservices). • Designed and built the payment service from scratch: PostgreSQL schema, payment lifecycle model and Monobank Pay API acquiring integration, from invoice creation to payment status handling. • Made payments atomic: the payment status update and the order transition run in a single PostgreSQL transaction. • Built a notification service for abandoned carts: cron scheduler, emails via the Gmail API (OAuth 2.0). • Extended the Product and Order services: endpoints, DTOs, inter-service gRPC contracts.