Денис

Denys Farafonov
Backend Developer / Integration Engineer
Backend Development | PHP | REST APIs | SQL Server | Oracle

Spain (open to remote)
[відкрити контакти](див. вище в блоці «контактна інформація»)
Mobile phone: [відкрити контакти](див. вище в блоці «контактна інформація»)

SUMMARY

Backend Developer / Integration Engineer with 10+ years of experience working with database-driven
business systems, backend logic, REST APIs, integrations, and data processing.

Strong background in Oracle and MS SQL Server, including complex SQL, stored procedures, database
optimization, business logic, and large-scale data processing.

Hands-on experience with REST API integrations, JSON-based workflows, automation, and maintenance
of production systems. Additional practical experience with PHP, JavaScript, and MySQL through web
application maintenance, SQL development, and freelance projects.

Currently expanding practical experience in modern web development, with a focus on backend
development and full-stack technologies.

KEY ACHIEVEMENTS

Reduced execution time of a high-load pricing query by 70–80% by refactoring Oracle SQL logic
using CTEs
Designed and implemented an automated returns processing system integrating with Nova Poshta
API
Restored system functionality within one day after breaking changes in an external Prom API
Built a monitoring system for background services, enabling proactive failure detection and
improving system reliability

PROFESSIONAL EXPERIENCE

Backend / Integration Engineer (MS SQL Server)

SMARTY UA (Ukrainian distributor of children's products) | Feb 2025 – Present

Develop and maintain backend logic for business-critical operations using MS SQL Server
Develop and maintain integrations with external REST APIs, including Nova Poshta and Prom
Build backend automation workflows for data processing and business operations
Process JSON payloads and implement business rules for API-driven workflows
Maintain and troubleshoot existing backend solutions and integrations

Key Contributions:

Designed and implemented an automated returns processing system integrating with Nova Poshta
API, reducing manual processing and improving operational efficiency
Built backend services for handling external API data and automating business workflows
Developed a monitoring system for background services, detecting repeated failures and triggering
alerts
Rapidly adapted backend logic to breaking changes in the external Prom API, rewriting MS SQL
procedures within one day to restore system functionality

Implemented backend logic for a B2B bonus system, processing JSON payloads and dynamically
adding bonus items to orders based on business rules
Designed API key lifecycle monitoring for Nova Poshta, including expiration tracking and automated
notifications

Database Engineer / Backend Developer (Oracle)

ISD Information Systems (partner of SCC Soft Computer, healthcare software solutions) | 2020 – Present

Develop and optimize complex SQL queries, stored procedures, and packages in Oracle DB
Develop and maintain backend data processing logic for business-critical systems
Optimize database performance using indexing strategies and execution plan analysis
Work with high-load datasets containing millions of transactions
Investigate production issues and modify existing backend/database logic to resolve them
Collaborate with business and engineering teams to improve data workflows and reporting

Software Developer

ISD Information Systems (partner of SCC Soft Computer, healthcare software solutions) | 2018 – 2020

Maintained and enhanced legacy systems using C++, PL/SQL, and enterprise tooling
Worked with multithreading and system-level logic
Supported backend components and data processing pipelines
Used SVN and worked in Unix/AIX environments

Embedded Software Engineer

Space Systems Engineering Ukraine | 2016 – 2017

Developed onboard control software using C/C++ on Linux-based systems
Worked with embedded systems, including Raspberry Pi, resource management, and system-level
programming
Used Git for version control

Backend Developer / Integration Engineer

BaDM Ltd (large pharmaceutical distributor) | 2012 – 2016

Developed and maintained database-driven backend systems using Oracle DB
Worked with PHP and JavaScript when modifying and maintaining existing web application code
Implemented business logic using stored procedures and backend services
Worked with REST APIs and backend integrations
Optimized database performance for large-scale internal systems
Supported internal web applications and backend integrations

Business Analyst (IT Department)

BaDM Ltd (large pharmaceutical distributor) | 2011 – 2012

Collected and formalized technical requirements
Participated in software validation and quality control
Worked with developers and business users to clarify application requirements

Analyst (Sales Department)

BaDM Ltd (large pharmaceutical distributor) | 2008 – 2010

Performed data analysis, including ABC/XYZ analysis
Analyzed sales and inventory data
Optimized delivery routes and supported sales forecasting

TECHNICAL SKILLS

Backend & Web Development

REST APIs, Webhooks, API Integration
Backend business logic and data processing
JSON, XML
Web application maintenance and troubleshooting
PHP — basic practical / maintenance experience
JavaScript — basic practical / maintenance experience
HTML, CSS

Databases

Oracle (PL/SQL)
MS SQL Server
MySQL — practical SQL experience
Complex SQL and stored procedures
Query optimization
Indexing and execution plans
Database design and data processing

Programming

C++, C#
PHP — basic practical experience
JavaScript — basic practical experience
Python — basic practical experience

AI-Assisted Development

ChatGPT — coding, debugging, code analysis, refactoring, SQL optimization, and technical
problem solving
Claude / Claude Code — code assistance, analysis, and technical documentation
Gemini — technical research, documentation lookup, and comparison of alternative approaches
Reviewing, validating, and adapting AI-generated code

Tools & Environment

Git, SVN
Linux/Unix

Languages

English (B2)
Spanish (basic, in progress)
Russian (fluent)
Ukrainian (fluent)

EDUCATION

Master’s Degree in Computer Science
National University of Dnepropetrovsk