Костянтин

Kostiantyn Volkov
iOS Developer
[open contact info](look above in the "contact info" section) | [open contact info](look above in the "contact info" section) | Ukraine
xj.kynex.tech | github.com/NeyerXj | Telegram
[open contact info](look above in the "contact info" section)

PROFESSIONAL SUMMARY
iOS Developer with 3+ years of commercial experience and freelance work since 2022. Builds SwiftUI and UIKit
apps from architecture to App Store release, including subscriptions, offline workflows and AI integrations.
Also owns Python and TypeScript backends: APIs, PostgreSQL, background queues, billing integration and
deployment. Develops Android apps with Kotlin and Jetpack Compose.

CORE SKILLS
iOS: Swift 6, SwiftUI, UIKit interoperability, MVVM, SOLID, Swift Package Manager (SPM), async/await, actors,
Sendable
APIs and storage: REST, URLSession, Codable, WKWebView, deep links, Core Data, Keychain, offline caching
Monetization and analytics: StoreKit 2, RevenueCat, Firebase Auth, Remote Config, AppsFlyer, Amplitude,
APNs, paywall A/B testing
Backend: Python, FastAPI, Node.js, TypeScript, NestJS, Next.js, PostgreSQL, Redis, background workers

PROFESSIONAL EXPERIENCE

iOS Developer
Midnight.Works | Remote | Sep 2025 - 25 Sep 2026
Shipped production SwiftUI features under NDA within a modular app architecture, focusing on stability and
performance.
Built navigation stacks, sheets and full-screen flows; integrated REST APIs with pagination, prefetching and
offline caching.
Implemented Firebase and Amplitude analytics to track product funnels and support product decisions.

Middle-Senior iOS / Full-Stack Developer
Polorix | Remote | Jan 2024 - Sep 2025
Owned iOS product delivery from architecture to App Store release, including API integration, testing,
debugging and support.
Built SwiftUI/UIKit interfaces, Core Data storage, StoreKit and RevenueCat subscriptions, authentication and
push notifications.
Developed FastAPI services for social/web ingestion, AI metadata extraction, OCR and media processing,
backed by PostgreSQL and Redis workers.
Deployed backend services with Docker Compose and Nginx; maintained persistent storage, health checks
and scheduled jobs.

Freelance iOS Developer
Self-employed | Remote | Feb 2022 - Sep 2024
Delivered apps with onboarding, authentication, paywalls, subscriptions, push notifications, offline caching
and App Store releases.
Built widget, keyboard and report extensions with shared storage through App Groups.

SELECTED IOS PROJECTS

Klad | Content organization and planning
App Store: apps.apple.com/app/id6754760495
Built SwiftUI collection and Explore flows, offline caching, RevenueCat subscriptions, analytics and push
notifications. Also developed the product backend and Android client.

Nexyra | Wi-Fi and LAN diagnostics
App Store: apps.apple.com/app/id6759560010
Built device discovery, port scanning, reports and network quality scoring with iOS networking APIs;
integrated RevenueCat and Amplitude Session Replay.

AuraWidgets | Home Screen widgets and trackers
App Store: apps.apple.com/app/id6759844756
Built WidgetKit photo widgets and interactive trackers with App Intents and App Groups; resolved memory
and performance issues.

Blockkr | Screen Time control
Implemented usage monitoring and blocking based on time and steps with FamilyControls,
DeviceActivityReportExtension and shared App Group state.

NureSchedule | University timetable
App Store: apps.apple.com/app/id6742908592
Built SwiftUI week/month calendars, schedule synchronization, MapKit routing and Look Around previews;
optimized calendar updates.

Superboard | AI keyboard
Built a KeyboardKit extension with voice input, AI responses, quick replies and App Group storage; reduced
input latency.

Arion | iOS messenger and real-time backend
Built a SwiftUI client and NestJS/WebSocket/PostgreSQL backend with delivery/read acknowledgments,
reconnect handling, call signaling, VoIP and APNs extensions.

APP STORE DELIVERY AND DEVELOPMENT WORKFLOW
Own App Store Connect signing, builds, TestFlight, metadata, publication and rejection responses; automate
releases with Fastlane (match, gym, deliver, pilot) and API keys.
Implement trials, introductory offers, restore purchases and purchase verification; maintain CI/CD, privacy
manifests and Required Reason API declarations.
Use Codex daily, Git and code review; generate and review assets, ASO metadata and localizations with AI
tools.

EDUCATION AND LANGUAGES
BSc Computer Engineering, Kharkiv National University of Radio Electronics (NURE) | 2024 - 2028 | In progress
English: B2 | Ukrainian: Native | Russian: Native | Spanish: A1

BACKEND AND FULL-STACK PROJECTS

Klad | AI content and product backend
Python, FastAPI, PostgreSQL, Redis, RQ, SQLAlchemy, Alembic
Built media ingestion and AI enrichment pipelines with OpenAI, Gemini, Whisper and Google Places;
developed feeds, recommendations, collections, reviews, quotas and admin tools.
Integrated JWT, Apple/Google authentication, subscription verification and APNs. Optimized SQL pagination
and batch queries to remove N+1 access.
Implemented outbox delivery with leases, retries and bounded database lock waits; moved retention work
off the request event loop while preserving legacy API contracts.

Forkeep | Recipe platform and subscription backend
Python, FastAPI, PostgreSQL, Redis, Celery, S3-compatible storage
Built APIs and workers that turn social video, images and text into structured, multilingual recipes, with
separate free/premium queues and provider fallback handling.
Implemented Apple/JWT authentication, RevenueCat entitlements, APNs, media delivery and offline sync
contracts; built analytics ingestion and admin reports.
Built a durable notification outbox with deduplication and retries; deployed Docker services with database
migrations, health checks and operational monitoring.

Retouva AI service | Asynchronous photo editing
TypeScript, Node.js, NestJS, Redis, BullMQ, OpenAI, Kie
Built job submission, status and result APIs with provider credentials kept on the server; separated API
requests from image generation workers.
Implemented idempotency, atomic queue admission, concurrency/rate limits and retry handling; tested
restart recovery and Redis/provider failures.

Kadro | Photo catalog API and admin
TypeScript, Fastify, React, PostgreSQL, Cloudflare R2, Sharp
Built uploads, bulk imports and multi-category photo management; added revision-aware pagination, batch
retrieval and image processing.
Delivered the React admin and deployed the API, landing page and storage integration with HTTPS; verified
production upload and retrieval flows.

ADDITIONAL ENGINEERING EXPERIENCE
Backend and web: Next.js, JavaScript, React, Vite, Starlette, Pydantic, WebSocket, HTML/CSS; REST APIs, admin
dashboards and Telegram bots
Infrastructure: Docker, Docker Compose, Nginx, Linux, SQL migrations, object storage, scheduled jobs, CI/CD
and monitoring
AI and media: PyTorch, Transformers, OpenCV, Pillow, Tesseract OCR, yt-dlp, HTTPX; transcription, metadata
extraction and translation APIs
Android and devices: Kotlin, Jetpack Compose; ESP32, Raspberry Pi, MQTT, USB/serial integrations and device
dashboards