Staff Engineer · Technical Lead
Oleksii Vasylenko
18 years shipping distributed systems, fintech, and cryptographic products. I work from low-level Rust services through typed SDKs and React interfaces, and I lead teams when the problem needs both architecture and delivery.
Brazil · UTC−3 · Remote
Full-time or contract (invoices via own Brazilian company)
ovasylenko.com · github.com/ovasylenko
Selected results
- Weeks → days
- release cycle · PropertyGuru
Core capabilities
- Node.js, TypeScript, NestJS, React, Rust
- Architecture leadership across remote teams
- Distributed systems and durable execution
- Matching engines and real-time market data
- PostgreSQL, Redis, RabbitMQ, Docker, AWS, GCP
- ZK proofs, smart contracts, and applied cryptography
Experience
Security Researcher at Independent Security Research
2026 - Present · Remote
- Conducted independent security research on Threshold Network / tBTC, reviewing its distributed threshold-signing client (Go) and bridge contracts (Solidity)
- Authored an Immunefi-style technical write-up and submitted it through coordinated responsible disclosure
Go · Solidity · Threshold Signatures (tECDSA) · Bitcoin · Lattice Cryptanalysis · Immunefi
Senior Backend Engineer, Real-time Systems at Walky
2025 - 2026 · Remote
- Built the real-time layer of Walky, a closed, .edu-verified social platform that moves college students from online-only contact to meeting in person, with a mobile app and a university admin dashboard
- Implemented live presence and location sharing over Socket.IO and Redis: which students are active nearby, invitations to meet, and private two-person rooms that drop out of the shared map while active
Node.js · TypeScript · Express · Socket.IO · Redis · React
Technical Lead / Full-Stack Developer at Bitsten exchange
June 2024 - Feb 2025 · Remote
- Architected matching engine processing 4000+ orders/sec with sub-millisecond latency
- Engineered liquidity bots integrating multiple market maker APIs, improving order book depth by 3x
React · Node · TypeScript · Nest · RabbitMQ · KeyDB
Web3 Developer at Panther Protocol
June 2023 - June 2024 · Remote
- Built zk-SNARK wallet engine supporting multiple blockchains with UTXO-based transaction model
- Identified and resolved critical vulnerabilities in Circom circuits during security audits
React · Service Workers · zk-STARK · zk-SNARK · Circom · Elliptic Curve Cryptography
Web3 Developer at Mailchain
March 2022 - June 2023 · Remote
- Integrated major blockchains including Ethereum, ENS, and Near for wallet-to-wallet messaging
- Created TypeScript SDKs with comprehensive documentation for third-party developers
React · D3 · Node.js · WebSockets · Ethers · Rollup · Webpack
Frontend Architect at PropertyGuru
April 2020 - March 2022 · Singapore
- Engineered unified payment service adopted across 4 product teams, eliminating duplicate code
- Implemented Webpack Module Federation reducing deployment coupling and release cycle from weeks to days
React · NestJS · D3 · Node.js · Tableau · WebSockets
Head of Product Development at Data Laboratories
August 2015 - December 2018 · Singapore
- Led team of 15 engineers across 3 time zones, shipping on tight deadlines
- Architected D3-based data visualization platform processing millions of data points in real time
React · D3 · WebSockets · .NET Core · CoffeeScript
Earlier work & education
Frontend Architect at ZuZu Hotels · Rust Developer at Kobvel Software Consulting · Senior Full-Stack Developer at Xen Technologies · Full-Stack Developer at Lohika
Bachelor of Computer Engineering with honors, Sevastopol National Technical University · English and Portuguese