
Oleg Filimonov
Verified Expert in Engineering
Prompt Engineering Developer
Dubai, United Arab Emirates
Toptal member since November 6, 2017
Oleg builds AI-powered web and mobile products with TypeScript, Next.js, React Native, and Expo. A full-stack developer with 11 years of experience, he created SLYK and has evolved it over five years, including three years of AI-assisted development. He uses Claude Code and Codex for product engineering, backed by typed APIs, automated checks, and release tooling for web, iOS, and Android.
Portfolio
Experience
- Artificial Intelligence (AI) - 3 years
- Large Language Models (LLMs) - 3 years
- Prompt Engineering - 3 years
- AI-assisted Development - 3 years
- LLM Integration - 3 years
- LLM Agents - 1 year
- Codex - 1 year
- Claude Code - 1 year
Preferred Environment
Claude Code, Codex, TypeScript, Next.js, React Native, Expo, Git, E2E Testing, Linear
The most amazing...
...project I created is SLYK, a platform for building web, iOS, and Android products with shared TypeScript code and AI-assisted workflows.
Work Experience
Mobile Apps Team Lead
Tapin Sports
- Led a team of React Native developers to create a complex enterprise-level mobile app.
- Created workflow guidelines, including code style guides, branching patterns, and team interaction guidelines.
- Built a fully managed automated workflow, including E2E UI testing, CI/CD, and automated store publishing.
Software Architect | Team Lead
Makeen
- Developed AI-assisted engineering workflows and supporting instructions for AI agents, alongside reusable tools for web and mobile product delivery.
- Built and maintained web and mobile applications with TypeScript, Next.js, React Native, Expo, tRPC, and PostgreSQL across healthcare, sports, commerce, and social products.
- Created native UI components and native modules for React Native applications on Android and iOS.
- Developed internal tools and shared application architecture to support development, validation, and release workflows.
- Led a team of 6 to 10 developers and coordinated engineering work using Jira and Slack.
Mobile Software Developer
Wirestorm
- Built native Android modules for React Native applications.
- Created a framework for React Native applications.
- Supported the development of multiple React Native applications.
Android Developer
Frevia
- Created an Android application called Frevia. It is an online multiplayer trivia game.
- Built fully custom animated UI components. Helped with UI/UX design of the application.
- Developed an Android module for handling video playback on multiple texture surfaces.
- Handled the publication of the application to the Google Play Store and helped with ad campaigns.
Lead Android Developer
After Class
- Created an Android application called Three Min Passion: it's a service that provides video lessons with interactive elements.
- Built a module for dynamically creating an Android layout with support for images, videos, text, and animation of the elements.
- Developed a JavaScript module for displaying a force-directed graph of content and connected it to the Android SDK.
- Led a small team of Android developers to provide additional features and support for the app.
Android Developer
App Fiction GmbH
- Created an Android application called Blanana: a social network that provides users with geo-location-based local chat with support for image messages.
- Managed the UI and UX design of the application.
- Provided support after the publication of the app.
- Integrated image content editing and verification.
Android Developer
Indoora
- Researched and created an algorithm for mapping custom rectangular maps onto a Mercator projection.
- Created an SDK for displaying custom-tiled maps from PNGs, multi-level maps, multi-level positioning, and navigation, based on the Google Maps API.
- Developed a Windows .NET application for slicing PNG maps into tiles with different levels of detail, based on ImageMagick.
- Created an Android application called Tuyap that uses the custom SDK. The features include dynamic theme switching and large dataset management.
Experience
SLYK | AI-assisted Web and Mobile Development Platform
https://www.slyk.aiThe stack combines Next.js, React Native, Expo, tRPC, PostgreSQL, Drizzle ORM, and Better Auth in a Turborepo monorepo. I built shared authentication, validation, UI, localization, analytics, notifications, and AI chat integrations.
SLYK also includes reusable skills and instructions for Claude Code and Codex, automated checks, dependency maintenance, and release tooling for Vercel and Expo. App-store metadata and screenshot workflows live alongside the code.
I use this foundation across Max by Catch America, Healthcare Strong, Vaulted, Zero Cal, Zero Chat, and Zero Wish, and bring reusable improvements back into SLYK. My work covers architecture, web and mobile development, back-end services, AI integration, and delivery.
Zero Chat | Multi-model AI Chat
https://zero-chat.appMy work includes streaming chat, model discovery, conversation persistence and search, personal memory, and usage accounting. The application uses the Vercel AI SDK and AI Gateway with Next.js, React Native, Expo, TypeScript, tRPC, and PostgreSQL. I also implemented authentication and subscription access.
Zero Chat builds on SLYK, my shared development platform, and uses AI-assisted engineering workflows with typed APIs and automated checks.
Max by Catch America | AI Fishing Assistant
https://catch-america.vercel.app/aiMy work includes AI chat, report review, lake data, administration, and Shopify integration. The Next.js and Expo applications share TypeScript services, tRPC APIs, authentication, and PostgreSQL data models.
The product uses SLYK as its development foundation. I work across the mobile and web interfaces, back-end services, third-party integrations, and delivery workflows, using AI-assisted development with automated validation.
Zero Cal | AI Calorie and Macro Tracker
https://zero-cal.appMy work includes food search, meal history, personal goals, logging streaks, weekly reports, reminders, and subscription access. The app supports English, Spanish, and Russian.
Zero Cal uses the SLYK architecture with React Native, Expo, TypeScript, Next.js, tRPC, and PostgreSQL. I develop the mobile interface, back-end services, AI integrations, and release tooling. Nutrition estimates remain editable so users can correct the results.
Zero Wish | AI-assisted Wishlists
https://zero-wish.vercel.appI implemented AI-assisted product research that returns structured, editable drafts. Price extraction checks source evidence before accepting a researched price, and unknown fields remain editable. Other work includes authentication, public list sharing, subscriptions, and localization.
The application uses Next.js, React Native, Expo, TypeScript, tRPC, PostgreSQL, and the Vercel AI SDK. It shares the SLYK foundation and its AI-assisted development workflows.
Tapin Sports
https://tapinsports.comMy responsibilities included mobile architecture, implementation, code review, and team development standards. I established code style, branching, and collaboration guidelines, and built delivery workflows with end-to-end UI testing, CI/CD, and automated store publishing.
The work combines React Native, TypeScript, Android, and iOS development, Firebase, and back-end integrations. I managed a team of up to five developers and supported the application through development and releases.
Vyoo Social Network
My work covered mobile application development for Android and iOS using React Native and TypeScript, with Firebase and back-end integrations. I worked on interfaces that help members discover communities, connect with people, coordinate meetups, and take part in events.
The project gave me experience building social and community products with communication, location-based discovery, and paid event workflows.
Ownage Pranks Real Prank Call
https://play.google.com/store/apps/details?id=com.prankcalllabs.prankcallappMy work focused on the mobile application and its user experience, bringing the content library and call-related workflows into an Android interface. The app reached more than 100,000 users in its first month.
This project represents my earlier native Android experience before expanding into React Native, Expo, and full-stack web and mobile development.
Sleep Time
https://play.google.com/store/apps/details?id=ru.olegfilimonov.sleeptimeI developed the Android and iOS application with React Native and worked on the user interface, user experience, and Firebase integration. The product turns a simple time calculation into an accessible mobile experience, with an emphasis on clear inputs and easy-to-read results.
Sleep Time is one of my independently developed consumer apps and forms part of my longer experience delivering and maintaining mobile products.
Healthcare Strong | Wellness for Healthcare Teams
https://healthxstrong.vercel.appMy work includes organization onboarding, member and administrator workflows, habit and challenge tracking, rewards, and notifications. The mobile app also supports optional Apple Health activity integration.
The Next.js and Expo applications use the SLYK architecture, with shared TypeScript packages, tRPC APIs, authentication, and PostgreSQL models. I work across product interfaces, back-end logic, integrations, testing, and delivery.
Vaulted | Athlete Collectibles and Fundraising
https://www.joinvaulted.com/marketplaceMy work includes player and club administration, card sets and editions, onboarding, auctions, offers, donations, and Stripe Connect payment integration. Shared APIs and PostgreSQL models support the Next.js and Expo applications.
The product builds on SLYK with TypeScript, React Native, tRPC, and reusable authentication and UI packages. I develop application architecture, web and mobile interfaces, back-end services, and delivery workflows.
Education
Master of Science Degree in Computer Science
Saint Petersburg State Electrotechnical University - Saint Petersburg, Russia
Bachelor of Science Degree in Computer Science
Saint Petersburg State Electrotechnical University - Saint Petersburg, Russia
Skills
Libraries/APIs
React, Node.js, Zod, React Query, NativeWind, Stripe Connect, Shopify API, Playwright
Tools
Git, Jira, Figma, Expo, Claude Code, Codex, Slack, Drizzle ORM, AI SDK
Languages
TypeScript, JavaScript
Frameworks
React Native, Next.js, tRPC, Tailwind CSS, Detox
Paradigms
E2E Testing
Platforms
Android, Firebase, iOS, Mobile, Amazon Web Services (AWS), Google Cloud Platform (GCP), Vercel
Storage
PostgreSQL, Redis
Other
Mobile App Development, AI-assisted Development, User Experience (UX), User Interface (UI), Artificial Intelligence (AI), LLM Integration, LLM Agents, Large Language Models (LLMs), Linear, Prompt Engineering, Turborepo, Better Auth, CI/CD Pipelines, Social Networks, Video Chat, Social, Cellular
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