Денис

Denys Farafonov
Backend / Integration Engineer (SQL Server / Oracle / APIs)
SQL Server | Oracle | REST APIs | System Integration

Spain (open to remote)
[open contact info](look above in the "contact info" section)
Mobile phone: [open contact info](look above in the "contact info" section)

SUMMARY

Backend and Integration Engineer with 10+ years of experience in database-driven systems, API
integrations, and performance optimization.

Specializing in Oracle and MS SQL Server, I design and optimize backend services, build REST API
integrations, and implement automation workflows using background services and webhooks.

Experienced in high-load enterprise environments (millions of transactions, large-scale data processing),
with a strong focus on performance, reliability, and maintainability.

Strong background in legacy systems, system integration, and rapid response to production issues.

KEY ACHIEVEMENTS

Reduced execution time of a high-load pricing distribution query by 70–80% by refactoring logic
using CTE (Oracle)
Designed and implemented automated returns processing system integrating with Nova Poshta API
Restored system functionality within one day after breaking changes in external Prom API
Built 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

Designed and implemented backend systems using MS SQL Server for business-critical operations
Developed and maintained integrations with external APIs (Nova Poshta, Prom, others)
Built background services for automation, data processing, and system workflows

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 (2+
consecutive errors) and triggering alerts, improving reliability and reducing downtime risks
Rapidly adapted backend logic to breaking changes in 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 (Nova Poshta), including expiration tracking and automated
notifications, preventing outages

Database Engineer / Backend Developer (Oracle)

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

Designed and optimized complex SQL queries, stored procedures, and packages in Oracle DB
Improved database performance using indexing strategies and execution plan analysis
Worked with high-load datasets (millions of transactions in enterprise systems)
Developed and maintained backend data processing logic for business-critical systems
Collaborated 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 (Raspberry Pi), including 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 backend systems using Oracle DB, PHP, and REST APIs
Implemented business logic via stored procedures and backend services
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

Analyst (Sales Department)

BaDM Ltd (large pharmaceutical distributor) | 2008 – 2010

Performed data analysis (ABC/XYZ)
Optimized delivery routes and sales forecasting

TECHNICAL SKILLS

Backend & Integration

REST APIs, Webhooks, API Integration
Backend data processing, system integration
JSON processing

Databases

Oracle (PL/SQL), SQL Server
Query optimization, indexing, execution plans

Programming

C++, C#, JavaScript, PHP

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