Vladislav

Vladislav Parfonov
Backend Software Engineer
Kyiv, Ukraine · [открыть контакты](см. выше в блоке «контактная информация») · [открыть контакты](см. выше в блоке «контактная информация») · [открыть контакты](см. выше в блоке «контактная информация»)

SUMMARY
Backend engineer with 9+ years of commercial PHP experience, the last 7 of them on a production industrial-IoT platform processing high-volume time-series
telemetry. Deep hands-on expertise in PHP 8, Laravel and Yii2, with a track record of turning performance and reliability problems into measurable results —
including a ~10x reduction in API response time (46s → 3s) and a test-coverage increase from 20% to 87% on a core business module.
Comfortable owning a feature end-to-end: requirements, architecture, implementation, tests, CI/CD and production support. Previously worked full-stack (React,
React Native, SCSS), which makes API contracts and frontend constraints easy to reason about. Regularly mentor junior and mid-level developers through code
review.

AREAS OF EXPERTISE
High-load REST API design and optimisation for web and mobile clients — profiling, query tuning, caching strategies.
Time-series and IoT data at scale: ingestion, storage and query optimisation on TimescaleDB (hypertables, aggregation).
Large-scale database migrations in production without downtime or data loss.
Layered, maintainable architecture — Clean / Hexagonal Architecture, DTO, Repository and Service Layer patterns, DI, SOLID.
Refactoring legacy codebases: extracting business logic from controllers, introducing clear boundaries and making code testable.
Raising test coverage and stabilising legacy business logic to make releases predictable.
CI/CD and deployment automation, containerised environments, cloud infrastructure.
Code review, mentoring and clear technical communication with engineers and stakeholders.

TECHNICAL SKILLS & PRACTICES

Languages & Frameworks PHP 7.x / 8.x, Laravel, Yii2, Symfony (learning), JavaScript, TypeScript basics
Architecture OOP, SOLID, Design Patterns, MVC, Clean & Hexagonal Architecture, Repository Pattern, Service Layer, Dependency
Injection
APIs & Messaging REST API design, JWT / OAuth, queue systems, third-party integrations, webhooks
Databases PostgreSQL, TimescaleDB, MySQL / MariaDB, MongoDB, Redis — indexing, query plans, partitioning
Performance Query optimisation, caching layers, high-load and time-series workloads, profiling
Testing & Quality PHPUnit, unit / integration testing, code review, static analysis
Cloud & DevOps AWS, Docker, CI/CD, GitHub Actions, Git, Linux, Nginx
Frontend (until 2023) React, React Native, jQuery, HTML5, SCSS, Vue (learning)
AI-Assisted Dev Claude Code, OpenAI Codex, Junie
Process Agile / Scrum / Kanban, Jira, Git flow, code review culture

JOB EXPERIENCE

WAITES 2018 – Present · Kyiv (Hybrid)
PHP / Backend Developer
Backend of an industrial IoT platform for predictive maintenance and equipment analytics. High-load time-series telemetry, complex domain logic, Yii2 and
Laravel codebases running side by side.
Contributed to the migration of high-volume time-series data from MariaDB to TimescaleDB, improving storage efficiency and query performance
across the platform.
Reduced API response time ~10x (46s → 3s) by redesigning data-retrieval logic for large datasets — reworked queries, indexes and aggregation strategy.
Built reliable processing and serving of large volumes of historical sensor data while keeping the system stable under continuous ingestion.
Co-developed the project's DTO layer, making DTOs a single source of truth for data structures shared across API, domain and persistence layers — removing
ad-hoc array passing and reducing serialization bugs.
Introduced a Repository layer to decouple business logic from persistence, which made the data access layer testable and interchangeable.
Extracted business logic from controllers into a Service layer, shrinking bloated controllers to thin HTTP entry points and enabling the coverage growth
above.
Improved overall application performance through database optimisation, indexing and multi-level caching.
Raised automated test coverage from 20% to 87% on a core business module, cutting regressions and increasing release confidence.
Set up automated deployment processes, reducing release time and manual overhead for the team.
Developed and maintained integrations with external services and cloud infrastructure (AWS).
Investigated and fixed critical production issues — caching inconsistencies, timezone bugs and transaction conflicts under load.
Worked closely with the backend team on shared architectural decisions and platform-wide conventions; supported junior and mid-level developers via code
reviews and knowledge sharing.
Stack: PHP 7.x/8.x, Laravel, Yii2, TimescaleDB, PostgreSQL, MariaDB, Redis, MongoDB, AWS, Docker, GitHub Actions, PHPUnit, Nginx, Linux

ViWeb 2016 – 2018 · Kyiv
PHP Developer
Development and support of PHP-based web applications for a range of client projects.
Implemented new features, fixed defects and refactored existing systems to improve maintainability.
Contributed across the stack (PHP, MySQL, JavaScript, HTML/CSS) to deliver production-ready code.
Worked directly with requirements and delivered features from specification through to release.
Stack: PHP, MySQL, jQuery, HTML5, CSS/SCSS, Git, Linux

EDUCATION
2016 – 2018 · Master's Degree, Software Development — Kherson State University
2012 – 2016 · Bachelor's Degree, Software Engineering — Kherson State University

LANGUAGES
Ukrainian — Native · Russian — Native · English — B1 (Intermediate), working level for technical communication