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HUBENKO DENYS
BACKEND DEVELOPER

CONTACT
Phone: [открыть контакты](см. выше в блоке «контактная информация»)
Email: [открыть контакты](см. выше в блоке «контактная информация»)
Address: Ukraine, Lviv
Links: LinkedIn

PROFILE
Backend developer with 3 years of experience across social, banking, betting, and IoT platforms. Particularly focused on
designing asynchronous, message-driven systems that stay reliable under failure — crash recovery, safe concurrency, and
consistent message delivery. Have driven several architectural decisions independently and delivered measurable performance
improvements through targeted database and caching optimizations.

PROFESSIONAL EXPERIENCE

11.2025 – Present Backend Developer | Sapling, Inc.
Python / FastAPI / asyncio / Redis Streams / PostgreSQL / CoAP / OpenThread / systemd / D-Bus / Jinja2 / JavaScript
● Initiated and drove architectural decisions for new services, choosing Redis Streams as the IPC/transport layer to fit the
resource constraints of a masterclock time-sync device managing a fleet of IoT devices.
● Optimized the metrics-preload pipeline from ~50s to ~2.4s by moving aggregation into PostgreSQL and using chunked
bulk writes to Redis, while introducing in-memory caching to reduce write frequency to the device's SD card and
preserve its limited write endurance.
● Refactored legacy code and built frontend features using Jinja templates and JavaScript in addition to core backend
work.
Transactional Email Delivery Service
● Replaced a legacy synchronous mailer with an async, queue-based email delivery service consuming jobs from Redis
Streams.
● Built crash-safe delivery with automatic reclaim of stuck messages, achieving reliable at-least-once delivery with no
lost emails on crash or restart.
● Designed retry and dead-letter handling that separates permanent failures (auth/config) from transient ones
(network/timeouts), avoiding duplicate sends.
IoT Device Job-Orchestration Worker (CoAP/OpenThread)
● Designed a scalable, asynchronous Redis Streams consumer to orchestrate updates over CoAP, capable of handling
concurrent job processing for hundreds of IoT devices, with PostgreSQL as the source of truth.
● Built dual-layer recovery — Redis stream reclaim for worker crashes, plus a PostgreSQL-backed watchdog with a
retry-count limit for stuck or failed jobs — ensuring no job is silently lost.
● Used atomic database operations for job state transitions to ensure safe concurrency across multiple workers,
preventing race conditions on the same job.
● Implemented concurrency control and backpressure to protect a bandwidth-constrained CoAP/radio gateway from
traffic spikes, keeping the device fleet stable under load.
● Integrated the worker with systemd and D-Bus for service lifecycle management and local IPC with device-facing
components.

6.2024 – 10.2025 Backend Developer | Insiders (Client projects)
Betting Platform
Python / Django / FastAPI / Celery / RabbitMQ / gRPC / WebSockets / SSE /PostgreSQL / Docker / Elasticsearch / Prometheus / Loki /
Grafana
● Extracted a custom admin panel into its own FastAPI service, improving scalability and maintainability of the platform.
● Implemented asynchronous workflows with Celery for handling heavy background operations and scheduling tasks.
● Built a notification service with WebSocket and REST API to provide real-time updates to users.
● Integrated RabbitMQ for reliable inter-service communication in a distributed system.
● Developed and maintained parsers and scrapers for collecting and processing data from external APIs.
● Replaced polling with Server-Sent Events (SSE) for real-time odds updates, reducing latency from ~30s to <1s and
eliminating revenue loss from stale odds.
Social Network Project
Python / Django / Django REST Framework / MySQL / Redis
● Designed and built a relationship-aware feed and filtering system from scratch, surfacing posts based on user
connections and their interactions.
● Designed the underlying data structures and APIs with Django REST Framework to support complex,
connection-based filtering at scale.
● Led the implementation of a caching layer using Redis, which reduced database load by 30%.
Banking Website
Python / Django / Wagtail / PostgreSQL
● Built a new membership signup flow, including SDK integration, to meet updated business requirements.
● Built new pages in Wagtail CMS matching design specs, along with reusable content components for editors to
assemble pages without developer involvement.
Horse Racing Platform
Python / Django / PostgreSQL / Django REST Framework / Redis
● Moved search, sorting, and filtering for race results from the frontend to the backend and refined the underlying SQL
queries, cutting response time from ~30s to ~1s.
● Introduced caching for frequently-accessed race data to further reduce load on the database.

11.2023 – 5.2024 Backend Developer | Independent Contractor — Food Delivery Platform
FastAPI / Django REST Framework / gRPC / WebSockets / Celery / Redis/ RabbitMQ / PostgreSQL / Docker / Docker Compose
● Developed backend features for orders, restaurants, menus, and user management using FastAPI and Django REST
Framework.
● Implemented the Outbox pattern with idempotent message handling to prevent message loss and duplicate notification
processing during retries and service restarts.
● Implemented background task processing with Celery for order processing and notifications.
● Used gRPC for communication between services.
● Built real-time notifications using WebSockets.

TECHNICAL SKILLS
● Django, Django REST Framework (DRF), FastAPI, Jinja2
● Django ORM, SQLAlchemy, Alembic, Pydantic
● PostgreSQL, MySQL, Redis, Redis Streams, Elasticsearch
● RabbitMQ, gRPC, CoAP, WebSockets, Server-Sent Events (SSE), Kafka
● asyncio, Celery, systemd, D-Bus
● Docker, Docker Compose, AWS
● Prometheus, Grafana, Alertmanager, Loki, Promtail
● Pytest, E2E testing, CI/CD, GitHub Actions
● System design, distributed systems, microservices architecture, IoT device management

EDUCATION
Lviv Polytechnic National University Graduated in 2026
Bachelor's Degree in Information Systems and Technologies

LANGUAGES
English — B2 Ukrainian — Native Russian — Native