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Danylo Bilous

@danylobilous

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Senior full-stack and mobile engineer building AI-native, scalable LLM products.

Canada

Message

What I'm looking for

I’m looking to build AI-native products end-to-end—scaling backend, web, and mobile while shipping production LLM/RAG features. I want a team where I can lead architecture, optimize cost/latency, and move fast with strong engineering practices.

I’m a Senior Full Stack & Mobile Engineer with 9+ years scaling production systems to 1M+ users. I focus on AI-native product engineering—shipping OpenAI and Anthropic Claude integrations, production RAG pipelines, and LLM-powered features that reduce inference costs and improve latency.

I bring full-stack depth end-to-end, from PostgreSQL schema design and NestJS APIs to AWS infrastructure and Expo/React Native mobile apps. I also build modern web frontends with Next.js and TypeScript, emphasizing clear architecture decisions and reliable delivery.

My strongest edge is production LLM engineering: integrating GPT-4o and Claude, building RAG with pgvector/Pinecone/Weaviate, and delivering agent workflows with tool/function calling and structured outputs. In the systems I’ve shipped, I’ve cut LLM inference costs by 40% and P95 latency by 55%, while improving throughput and team delivery velocity.

I’m also an engineering leader who stays hands-on—leading 7-engineer teams to on-time sprint delivery and building team practices like CI gates, PR reviews, and prompt/eval workflows. From fintech SaaS platforms to mobile-first experiences and AI avatar products, I love transforming complex ideas into scalable, production-ready platforms.

Experience

Work history, roles, and key accomplishments

Current

Lead Full Stack Engineer

Current

Mascotte.AI

Nov 2024 - Present (1 year 7 months)

Architected and led delivery of a B2C AI avatar SaaS, shipping 67 pages, 50+ API routes, real-time 3D avatars, voice chat, and an admin panel across 12 languages. Migrated a Next.js monolith into a decoupled B2B developer platform and built a real-time voice AI pipeline with per-avatar prompts and RAG, enabling a new B2B revenue channel.

Next.js TypeScript MySQL AWS RDS OpenAI API

Senior Full Stack & Mobile Engineer

VulnCheck

Jan 2024 - Sep 2024 (8 months)

Architected a fintech SaaS platform scaling to 1M+ active users, cutting system latency by 35% and increasing API throughput by 20%. Built production RAG and multi-step LLM agent workflows (tool calling, guardrails, retries), reducing inference costs by 40%, P95 latency by 55%, and deflecting 30% of support tickets; led an Expo/React Native app that reached 40% of platform traffic within 6 months.

NestJS PostgreSQL Anthropic: Claude RAG (Pgvector Hybrid Search)React Native AWS Infrastructure

Principal Engineer & Manager

Mercury Dasha

Sep 2022 - Dec 2023 (1 year 3 months)

Led and mentored a 3-engineer team to 100% on-time sprint delivery with Jest/React Testing Library coverage gates above 85%. Integrated OpenAI GPT-4 and embeddings for search and recommendations, lifting engagement by 25% and driving an 18% revenue increase, while architecting distributed Redis and a NestJS/MongoDB API layer to absorb 3x traffic growth and reduce deploy failures by 90%.

Text Embedding Ada 002 Redis NestJS MongoDB Jest React Testing Library

Full Stack & Mobile Engineer

PXN Phantom Network

Mar 2019 - Jul 2022 (3 years 4 months)

Delivered 30+ production features on a high-traffic global platform with Jest/React Testing Library and zero post-release regressions. Shipped early OpenAI-powered features that reduced response time by 45%, built an Expo/React Native app reaching 250k+ downloads, and led a migration from a legacy PHP monolith to Next.js/TypeScript and Django REST to improve maintainability by 40% and cut onboardi

Next.js Django REST Framework PostgreSQL AWS React Native Prisma Jest SSR SSG Optimization

Full Stack Developer

Node Audio Ltd

Jun 2018 - Dec 2018 (6 months)

Resolved critical MongoDB performance regressions by profiling queries, redesigning indexes, and rewriting aggregation pipelines, reducing P95 execution time by 35%. Architected an AWS CI/CD pipeline with CodePipeline, EC2, Docker, health checks, and automated rollback to sustain 99.9% uptime and cut deployment time from 45 to 8 minutes; implemented stateless JWT auth with refresh rotation and RBA

MongoDB Aggregation Pipelines AWS CodePipeline EC2 Docker JWT Refresh Token Rotation RBAC CI CD

Full Stack Developer

Fleamint

Feb 2015 - Apr 2017 (2 years 2 months)

Architected a payment processing system with third-party gateway integration, idempotent retries, and webhook handling, reducing transaction failure rates by 18% and supporting $2M+ monthly processing volume. Built scalable marketplace modules (catalog, cart, order management, and seller dashboards) to increase checkout speed by 22% and supported growth from hundreds to thousands of daily transact

Payment Integration Webhooks Idempotent Processing Marketplace Order Management Checkout Optimization Technical Feasibility