Contact information

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Work experience

Backend програміст

from 08.2025 to now (8 months)

- Engineered FastAPI microservices (PostgreSQL + Redis) ingesting 200k+ records/day with <100 ms p95 latency.
- Built Scrapy + Playwright pipelines with captcha bypass, retries & deduplication — 99%+ delivery rate.
- Designed RabbitMQ-driven ETL workflows replacing manual exports, cutting processing time by ~60%.
- Delivered Shopify-compatible CSV exporters handling complex product/variant logic for e-commerce clients.
- Extract data from websocket in real-time and save to database

Backend програміст

from 09.2023 to 08.2025 (2 years)
Dex223, Дистанційно (IT)

- Built REST & GraphQL APIs aggregating on-chain and off-chain data, powering live DeFi.
- Developed async FastAPI services + Redis caching serving 1M+ daily events with high availability.
- Created Web3.py event listeners and ETL pipelines for marketing analytics and user attribution.
- Build custom CRM for marketing department for optimize inner process

Backend Developer & Data Delivery

from 08.2022 to 09.2023 (1 year 2 months)
Callisto Enterprise, Дистанційно (IT)

Developed and supported backend services for corporate clients.
Integrated blockchain technologies using Web3.py, Ether.js, and Hardhat.
Optimized web application performance and security.
Make API use FastAPI

Python developer

from 06.2021 to 08.2022 (1 year 3 months)
DataOX, Миколаїв (IT)

- Scraped and processed 10M+ rows of structured data using Scrapy, - BeautifulSoup, and Pandas.
- Built Flask/Django internal APIs; optimised slow queries cutting average pipeline runtime by 35%.
- Creating scripts for automation with Selenium

Python developer

from 03.2020 to 06.2021 (1 year 4 months)
Upwork - Freelancer, Дистанційно (IT)

- Developed Python & Node.js backend solutions for 10+ international clients across e-commerce and SaaS.
- Automated deployment and scaling with AWS (EC2, S3) and Docker; achieved 99.5% uptime SLA.

Education

КПІ

ФПМ, прекладна математика, Київ
Higher, from 2015 to 2019 (4 years)

Knowledge and skills

• Python
• Git
• SQL
• FastAPI
• PostgreSQL
• Redis
• MongoDB
• Elasticsearch
• Scrapy
• Playwright
• Selenium
• Pandas
• NumPy
• OpenCV
• Celery
• FastStream
• RebbitMQ
• Django
• Django Rest Framework
• Flask
• Web3.py
• TheGraph
• SQLAlchemy
• DjangoORM
• HTML
• CSS
• JavaScript
• Docker
• Kubernetes
• AWS
• Docker Compose
• REST API
• GraphQL
• ChatGPT API

Language proficiencies

• Ukrainian — fluent
• English — average

Additional information

Kostya Ostapenko

Contact:
e-mail: [open contact info](look above in the "contact info" section)
telegram @kostya_ostapenko

Python Developer with 5+ years delivering production-grade backend systems, high-throughput data pipelines, and
automation platforms. Built distributed scrapers processing 200k+ records/day, async FastAPI services handling
millions of events, and blockchain data APIs powering live DeFi products. Strong ownership mindset — from
architecture to deployment.