Nikolai K.

$45USD/hour
Madrid, Community of Madrid, Spain
Full-time (40 hrs/week)

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I'm a Python Backend Developer with over 9 years of experience. I'm proficient in Python, with expertise in Django, FastAPI, asyncio, and AI-driven applications. My background includes database management and ETLs, blockchain technologies(Bitcoin, Ethereum, Solana), microservice architectures, and DevOps practices. I have a passion for software quality and mentoring others. Spearheading technology at Book For Work, I ensure our B2B hotel booking platform remains one of Italy's leading tools.

Skills

Python 9 yrs
PostgreSQL 7 yrs
FastAPI 3 yrs
Amazon CloudWatch 5 yrs
SQLAlchemy 5 yrs
API Development 5 yrs
Microservices 5 yrs
Software Development 9 yrs
Distributed Systems 5 yrs
Celery 2 yrs
Extract, Transform, Load (ETL) 3 yrs
Team Leadership 1 yrs
Nginx 3 yrs
Cloud Applications 4 yrs
Continuous Integration and Continuous Delivery (CI/CD) 5 yrs
Cloud Computing 4 yrs
Rust (Programming Language) 1 yrs
Django REST Framework 2 yrs
RabbitMQ 2 yrs
Node.js 1 yrs
React.js 1 yrs
Amazon Web Services (AWS) 5 yrs
Kubernetes 2 yrs
JavaScript 2 yrs
Apache Kafka 3 yrs
GraphQL 3 yrs
Amazon EC2 5 yrs
AsyncIO 5 yrs
Django 7 yrs
Docker 6 yrs

Experience

Principal Software Engineer

Book For Work 2 yrs 1 mo

A B2B hotel booking platform that sells to companies and travel agencies and allows them to customize settings such as travel policies, user management, etc. The #1 B2B booking tool in Italy. Finalists at the Italian Mission Awards 2019, 2020, 2021, 2022.
Key responsibilities:
- Leading the development of version 2.0 of the software platform h-trips.com (bookforwork.com).
- Implementing improvements and optimizing workflows to enable further scaling.
- Planning the infrastructure to ensure the reliability and stability of services
- Planning and designing the architecture for critical features.
- Managing communication with API providers to ensure effective integration.

Python Software Engineer

ZUBR 3 yrs 6 mos

Zubr: a centralized cryptocurrency exchange. One of the first professional crypto-currencies exchange and corresponding ecosystem in the world with real high frequency matching engine.
Key technical achievements include:
- Implemented an Ethereum blockchain payment system for the exchange (CEX).
- Developed a Kafka-checker application for debugging the data bus, designed for use by developers and DevOps team.
- Created a partner rebate program service, enabling authorization with the ability to distinguish partner keys from regular ones, and facilitating the transfer of commission profits from each client's transaction to the respective partner.
- Implemented monitoring for Python microservices to enhance system reliability with Sentry and Prometheus/Grafana.
- Maintained and developed new GraphQL methods for the CEX admin panel.
- Maintained and improved the Bitcoin blockchain payment system and other CEX services, including trading bots, user sessions and authentication, registration, and KYC (Know Your Customer) processes.
- An indexer app for storing, aggregating and calculating historical DeFi protocol data is implemented

Python Software Engineer

Improvado 2 yrs

SaaS solution for aggregation and visualization for marketers.
Key technical achievements include: - Implemented new integrations with advertising platforms: Integrated ActiveCampaign, Pepperjam, and Salesforce into the system. Issues solved: a. Addressed a race condition between workers in a distributed system when obtaining auth tokens by implementing a Redis-based mutex. Managed concurrent API connection limits using a Redis-based semaphore. - Developed solutions using Google Spreadsheets as client UI with corresponding server endpoints to enhance usability. - Upgraded app data downloader architecture from in-memory queues (Python multiprocessing library) to persistent queues using RabbitMQ. Issues solved: a. Prevented excessive loading and worker stacking by introducing a ratio constant to balance the number of fast and slow tasks in the queue. b. Mitigated the risk of app crashes during modifications by writing comprehensive integration tests. c. Reduced database load by grouping tasks with similar parameters for batch database queries, optimising overall performance.

Fullstack developer

S Media Link, LLC 1 yr 10 mos

Patient’s Portal: A GUI app for a medical self-service interactive kiosk, designed specifically for the U.S. market.
Key technical achievements include: - Implemented GUI layouts and logic using the Kivy framework. - Integrated drivers for measuring devices (thermometer, scales, pressure meter). - Developed custom image mapping for selecting trouble body parts and related symptoms. - Managed a team of four developers and onboarded new team members at the company branch. • FindFriend: iOS App for Location Tracking of Family, Friends, Spouses, etc. Key technical achievements include: - Developed REST APIs for user data, authentication, and processing and broadcasting location data using WebSockets. - Implemented visibility rules for different user lists (friends, family, blacklist, etc.).