Арсен

ARSEN SKLIARENKO
Middle+ Backend Engineer
PHP · Yii2 · Symfony · Microservices · Distributed Systems · Backend Engineering
[open contact info](look above in the "contact info" section) | Ukraine | [open contact info](look above in the "contact info" section)

PROFESSIONAL SUMMARY
Backend engineer with 3+ years of production PHP experience, building and maintaining backend services at Lalafo.
Experienced in Yii2 and Symfony, microservice integration, REST APIs, asynchronous processing, and production
reliability. Strong working knowledge of Symfony’s service container, dependency injection, autowiring, configuration,
and console commands. Hands-on with RabbitMQ, Kafka, PostgreSQL, Redis, search infrastructure, observability, and
AI/LLM integrations. Focused on maintainable code, data consistency, testing, and predictable behavior under load.

CORE TECHNICAL SKILLS
Languages & Frameworks: PHP 8.3, Yii2, Symfony, REST API design, Composer, PSR standards, dependency injection,
service container
Databases & Storage: PostgreSQL, MySQL, Redis, Elasticsearch, OpenSearch, ClickHouse, InfluxDB, AWS S3
Messaging & Async: RabbitMQ, Apache Kafka, workers and consumers, retries, dead-letter queues, idempotent
processing, event-driven workflows
Infrastructure: Docker, Kubernetes, Helm, CI/CD pipelines, AWS, ingress-nginx
Observability: Grafana, Prometheus, Graylog, Kibana, structured logging, custom metrics and alerting
Testing & Quality: Codeception, PHPUnit, PHPStan, PHP CS Fixer, integration testing with and without mocks
AI / LLM: LiteLLM integrations, prediction pipelines, prompt versioning, model fallback, circuit breaker, request
metadata

ENGINEERING EXPERTISE
• Microservices and API design
• Symfony application structure, services, dependency injection, configuration and console commands
• RabbitMQ and Kafka workflows
• Reliability patterns: retries, timeouts, dead-letter queues, fallback and circuit breaker
• Database performance and consistency
• Production observability, metrics, alerting and incident debugging

PROFESSIONAL EXPERIENCE
Backend Engineer, Lalafo | Sep 2024 – Oct 2026
Classifieds platform
Develop and maintain production backend services supporting millions of ads and users, with a focus on backend
features, cross-service integration, reliability, data quality, and asynchronous workflows.
• Designed a Redis-backed circuit breaker and model-fallback flow for AI predictions, coordinating state across workers
and preserving queue behavior on failure.
• Built an asynchronous bulk-import pipeline with isolated RabbitMQ workers, user-confirmation flow, retries, per-item
status tracking, and S3 image processing.
• Implemented a controlled workflow for testing moderation rules against real ads, including draft and production states,
batch comparisons, confidence analysis, and safe rollout.
• Introduced prompt-version tracking and correlated logging across LiteLLM requests, Kafka consumers, RabbitMQ
workers, and application components.
• Improved production Redis log storage to avoid oversized values and support backward-compatible reads.

PHP Backend Developer, Danavero Inc. | Feb 2023 – Feb 2024

SELECTED ENGINEERING HIGHLIGHTS
AI Fraud Detection and Moderation Tools
• Built an admin interface for managing AI fraud-detection prompts, validation rules, and model selection.
• Migrated fraud-detection requests from a direct Gemini integration to LiteLLM, enriching each request with ad
identifiers, country information, and contextual metadata.
• Improved observability of fraud-rule bypasses in chat workflows and enhanced moderation logic based on user
fingerprints and hashes.

Arsen Skliarenko | 1

AI Posting and Prompt Management
• Implemented versioned prompt management with release controls, admin editing, and role-based access control.
• Built a bulk prompt-evaluation pipeline (admin forms, REST endpoints, RabbitMQ queues and consumers) with
configurable batches, offsets, countries, and prompt versions.
• Improved single-ad generation: title editing, description handling, category prediction, preservation of photos and
attributes, and negotiable-price metadata.
AI Analytics, Search, and Provider Evaluation
• Added request-latency and input-text tracking across multiple microservices, plus per-prediction model attribution, to
analyze generation quality and performance.
• Integrated AI-generated titles, descriptions, and product types into Elasticsearch and OpenSearch indexes, using
denormalized metadata for more efficient indexing.
• Evaluated AWS AI capabilities against Gemini and implemented supporting image cleanup and URL-generation checks.
Business Profile and Bulk Ad Import
• Developed backend endpoints for a new business-profile ad management interface: awaiting-publication views, bulk
publication of temporary ads, and flexible filtering and sorting.
• Added search-backed ad counters, required-parameter metadata, and country options, and removed sensitive
fraud-related data from API responses.
• Developed endpoints for file-based bulk ad posting and fixed photo uploads, incorrect price-to-row mapping in large
files, and duplicate ad attributes.
Warehouse and Fulfillment Operations
• Built token-authenticated webhook endpoints for warehouse order collection and batch SKU lookup for product data.
• Implemented monitoring of order-status synchronization between the marketplace, fulfillment, and warehouse
management systems using ClickHouse and Grafana.
• Delivered warehouse workflow improvements (barcodes, storage locations, labels, product handling, InPost warehouse
addresses) and added Codeception tests for WMS endpoints.
Database Performance and Code Quality
• Improved database performance with new indexes across marketplace, CRM, fulfillment, branding, user,
business-profile, and other backend services.
• Optimized fraud-data cleanup and contributed to a code-quality initiative spanning nine microservices: resolved
PHPStan issues, added Codeception tests, improved event-service reliability, and strengthened quality checks.
Messaging, Security, and Infrastructure
• Moved Kafka subscriptions into a dedicated queue and worker to improve separation of responsibilities.
• Addressed dependency vulnerabilities and configured Composer security auditing in CI/CD.
• Fixed duplicate administrator accounts caused by inconsistent email casing during Azure and Teams authentication.
• Migrated an internal service to a new internationalization component, configured a development container, and created
an AI-assisted technical documentation workflow.
Observability and Production Monitoring
• Created Grafana dashboards and alerts for AI Posting, processing flows, and message queues.
• Added InfluxDB metrics to detect interruptions in ad generation and to support feature analytics.
• Improved structured logging, production diagnostics, and visibility into asynchronous processing across services.
Product-Specific Business Logic
• Implemented country-specific currency restrictions for Kyrgyzstan while preserving ad posting, editing, and search.
• Developed a v3 exchange-rate endpoint converting USD to the national currency without disrupting related workflows.

EDUCATION
Master’s degree, Cherkasy State Technological University
GeekHub courses | May 2021 – Jun 2022

LANGUAGES
Ukrainian: Native | English: B2

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