# Oleksii Vasylenko — I build the systems your business can't afford to get wrong ## About Oleksii Vasylenko takes on the engineering problems others avoid. 18+ years shipping production systems across fintech, crypto, and enterprise. Built matching engines processing 4000+ orders/sec, zero-knowledge proof wallets, and cross-chain messaging protocols — three different domains, all production, all shipped. Led teams of up to 15 engineers across 3 time zones. From React to Rust, architecture to implementation — he owns the full stack and the full outcome. ## Currently Available for remote technical leadership, complex system design, and senior individual contributor roles. Open to contract and full-time. Hire page: https://www.ovasylenko.com/hire ## Deep Dives — Architecture & Production Lessons These pages go beyond the resume bullet points. Each covers the architecture decisions, failure modes, and production lessons behind a specific domain. - ZK-SNARK Development — From Circuits to Production Wallets: https://www.ovasylenko.com/expertise/zk-snark Circuit-level security audits, UTXO wallet engines, and browser-optimized proof generation at Panther Protocol. - Building Matching Engines — Sub-Millisecond Order Processing: https://www.ovasylenko.com/expertise/matching-engines State management, order book design, and the candle engine rebuild for a live crypto exchange processing 4000+ orders/sec. - Micro Frontend Architecture — Scaling Teams, Not Complexity: https://www.ovasylenko.com/expertise/micro-frontends Monolith-to-micro-frontend migration at PropertyGuru for 4 independent product teams. - Rust and WebAssembly — Native Performance in the Browser: https://www.ovasylenko.com/expertise/rust-webassembly Rust-to-WASM compilation for blockchain clients, cryptographic operations, and Solana smart contracts. - Smart Contract Development — Solidity to Solana: https://www.ovasylenko.com/expertise/smart-contracts Production smart contracts across Ethereum and Solana — ERC-20 tokens, NFT marketplace programs, and ZK privacy layers. - Real-Time Systems — WebSockets, Message Queues, and Live Data: https://www.ovasylenko.com/expertise/real-time-systems Backpressure handling, snapshot-plus-diff patterns, and streaming pipelines for trading platforms and enterprise dashboards. - D3.js and Data Visualization — Making Data Tell Stories: https://www.ovasylenko.com/expertise/d3-data-visualization 7 years of D3 across 3 companies. Real-time dashboards, flight route maps, and executive analytics. - Cross-Chain Protocols — Connecting Blockchains: https://www.ovasylenko.com/expertise/cross-chain-protocols Protocol abstraction layers, wallet adapter patterns, and TypeScript SDKs — Ethereum to Near to ENS in one interface. - Frontend Architecture for Financial Systems — When Every Frame Counts: https://www.ovasylenko.com/expertise/fintech-frontend-architecture 60fps order books, offline-capable booking systems, and Core Web Vitals optimization for trading and payment UIs. - Database Architecture and Performance — Designing Data Systems That Scale: https://www.ovasylenko.com/expertise/database-architecture Polyglot data architecture — PostgreSQL, MongoDB, Redis, KeyDB — choosing the right database per workload. - Rust for Mission-Critical Systems — Why Rust When Failure Is Not an Option: https://www.ovasylenko.com/expertise/rust-mission-critical Ownership model eliminates data races, use-after-free, and null dereferences before production. Matching engines, workflow orchestrators, and cryptographic pipelines built in Rust. - Durable Workflow Engine Architecture — Beyond Temporal, Snapshot-Based Execution: https://www.ovasylenko.com/expertise/durable-workflow-engines Solo-built a Temporal alternative in Rust. 7-crate workspace, snapshot-based state persistence, O(1) resume, no history replay, no determinism constraints. - Lattice Cryptanalysis — LLL, BKZ, and Sieving in Production Rust: https://www.ovasylenko.com/expertise/lattice-cryptanalysis Solo-built g6k-rs, a 16K-line Rust lattice reduction library: LLL, BKZ 2.0, three sieve algorithms, CVP solvers, Coppersmith, LWE attacks, and ECDSA key recovery from partial nonce leakage. - Post-Quantum Cryptography Tooling — Optimizing the Leading Lattice Sieving Toolkit: https://www.ovasylenko.com/expertise/post-quantum-cryptography-tooling Performance engineering on G6K's C++ sieving engine and a 100× faster Rust spherical code generator with incremental Gram matrix updates for SimHash probe banks. ## Writing - How I Made G6K's Spherical Code Generator 100× Faster (June 2026): https://www.ovasylenko.com/blog/g6k-spherical-code-generator-100x-faster Incremental Gram matrix updates turn O(N·n) per-swap cost into O(N); Rust rewrite of the leading lattice sieving toolkit's code generator with byte-identical output. - How to Become a Protocol Developer: A Comprehensive Guide (December 2024, Medium): https://medium.com/@oleksii.vasylenko/how-to-become-a-protocol-developer-a-comprehensive-guide-42cad52a2f77 ## Work Experience - Bitsten exchange (June 2024 - Feb 2025): Full-Stack Developer. Architected matching engine processing 4000+ orders/sec with sub-millisecond latency. Built WebSocket-based trading system for thousands of concurrent users. - Panther Protocol (June 2023 - June 2024): Web3 Developer. Built zk-SNARK wallet engine supporting multiple blockchains. Identified and resolved critical vulnerabilities in Circom circuits. - Mailchain (March 2022 - June 2023): Web3 Developer. Integrated Ethereum, ENS, and Near for wallet-to-wallet messaging. Created TypeScript SDKs for third-party developers. - PropertyGuru (April 2020 - March 2022): Frontend Architect. Led monolith to micro frontend migration for 4 teams. Engineered unified payment service adopted across all product teams. - ZuZu Hotels (January 2020 - April 2020): Frontend Architect. Implemented PWA features for offline booking. Singapore. - Kobvel Software Consulting (November 2019 - January 2020): Rust Developer. Developed smart contracts for Solana's Metaplex NFT marketplace. Implemented Rust to WebAssembly compilation. - Xen Technologies (December 2018 - November 2019): Senior Full-Stack Developer. KYC/AML integrations and ERC-20 smart contracts. Singapore. - Data Laboratories (August 2015 - December 2018): Head of Product Development. Led team of 15 engineers across 3 time zones. Architected D3-based data visualization platform. Singapore. - Lohika (May 2011 - August 2015): Full-Stack Developer. Built real-time flight data visualization for travel agents. Integrated Amadeus GDS. Odessa, Ukraine. ## Personal Projects - scam.travel (https://scam.travel) — Crowdsourced travel scam database with 134+ real scam reports worldwide - Lattices.io (https://lattices.io) — Interactive educational reference for post-quantum cryptography with 3D lattice visualizations - TRounds (https://trounds.com) — Tabata/HIIT interval timer app with Spotify integration - Trading Statement (https://tradingstatement.io) — Fintech analytics platform for traders - Skillcrucial.com (https://skillcrucial.com) — Online coding school, 3,000+ users - Mynft.is (https://mynft.is) — NFT portfolio dashboard ## Teaching & Community - Skillcrucial: Founded and mentored 3,000+ developers through JavaScript and React curriculum - ZK-monk (https://www.zkmonk.org): Lecturer on Elliptic Curve Cryptography and zero-knowledge proof mathematics ## Contact - Email: hello@ovasylenko.com - Website: https://ovasylenko.com - GitHub: https://github.com/ovasylenko - Twitter: https://twitter.com/_alphaGeek - Medium: https://medium.com/@oleksii.vasylenko - StackOverflow: https://stackoverflow.com/users/3815605/rocktheworld ## Core Skills - React, Next.js, TypeScript, Node.js - Rust, WebAssembly, Systems Programming - Zero-Knowledge Proofs, Cryptography, Blockchain - Software Architecture, Distributed Systems - D3.js, Data Visualization, Real-Time Systems - PostgreSQL, AWS, Docker, Kubernetes ## Education - Bachelor of Computer Engineering (With Honors) — Sevastopol National Technical University (2006-2011) - Focus: Systems programming, distributed computing, cryptography ## Portfolio View full portfolio and work experience at https://ovasylenko.com