Sergei S., Blockchain Engineer
B2 (Upper-Intermediate) English
Senior (5-10 years)
Warsaw,
Poland
Summary
- Blockchain Developer with 5 years of experience building decentralized applications (dApps) using Solidity and Rust across EVM-compatible chains (Polygon, BSC, Base) and Solana.
- Proficient in frameworks such as HardHat and Anchor for developing, testing, and deploying smart contracts, with hands-on experience integrating wallets like MetaMask and working with DeFi protocols including Uniswap, Aave, and Alpaca Finance.
- Experienced in implementing and customizing token standards such as ERC-20, ERC-721, ERC-721A, and ERC-1155, as well as secure signing mechanisms via EIP-712.
- Skilled in smart contract auditing and fuzz testing using tools like Slither, Mythril, and RustSec, ensuring robust and secure codebases.
- Adept in version control and collaboration using Git and GitHub, with a focus on maintainable and testable code.
- Experienced in blockchain data indexing and integration using The Graph/Subgraphs, enabling efficient access to on-chain data across applications.
- Well-versed in cross-chain development and decentralized identity (DID), contributing to secure, scalable, and user-centric Web3 ecosystems.
Main Skills
Solana 1 yr.
Solidity 4 yr.
Programming Languages
Rust Libraries and Tools
JavaScript Libraries and Tools
JavaScript Frameworks
Python Libraries and Tools
BlockChain and Decentralized Software
Version Control
Other Technical Skills
Experience
DEFI ECOSYSTEM HUB
04.2023 - till now
Description: DeFi Ecosystem Hub offers next-generation decentralized finance (DeFi) products built on DeFiChain, a Bitcoin-based blockchain that incorporates native DeFi capabilities.
Responsibilities:
- Blockchain development;
- Design project architecture;
- Prepared reports summarizing audit findings and recommendations for improvement;
- Integration with Wormhole;
- Integrated with new blockchains and side-chains to increase the multichain infrastructure;
- Implemented buy and burn algorithms;
- Optimized performance of blockchain applications and smart contracts;
- Developed smart contracts for various DeFi products;
- Integrated with decentralized exchanges and other DeFi protocols;
- Updating and maintaining smart contract code and associated documentation as required to ensure accuracy and adherence to evolving standards;
- Maintained up-to-date knowledge of emerging blockchain and Python technologies, and led the adoption of best practices within the team;
- Contributed to high-level architectural decisions for blockchain infrastructure and software systems, ensuring alignment with business goals;
- Implemented EIP-712 for secure and efficient signatures;
- Implemented robust security measures for all smart contracts to safeguard users' assets;
- Created comprehensive documentation for smart contracts, integration processes, and architecture design;
- Analyzed and refined transaction processing to improve throughput and user experience;
- Code review.
Environment: Python, Solidity, Hardhat, Solhint, Wormhole, Base, Slither, Mythril, ERC-20, ERC-1155, ERC-721, ERC-721A, EIP-712, Web3.py, Pyth, Subgraphs, Aave, DAO, DeFi Metachain, Uniswap v2/v3, GitHub.
INVESTMENT PLATFORM
06.2021 - 04.2023
Description: Platform for investment in digital assets. The De-Fi platform combines a variety of broad functionality that makes it easier to work, the automation of many functions makes the user's work easier.
Responsibilities:
- Blockchain development using appropriate technologies and frameworks;
- Blockchain integration into applications, developing APIs and ensuring compatibility;
- Smart contract development to automate processes, manage assets, and enforce business rules;
- Custom algorithm development to address specific blockchain requirements;
- ERC-721 implementation for NFTs;
- ERC-20 token development;
- Wallet integration for storing and managing digital assets;
- Build wallet connection UI using Wagmi hooks within React components;
- Smart contract development for blockchain migration;
- Mentoring new developers on blockchain concepts and best practices;
- Code review to ensure quality, identify issues, and enforce standards.
Environment: Solidity, JavaScript, TypeScript, ethers.js, Wagmi, React, HTML/CSS, web3.js, Wallets integration(Metamask), EVM networks, Polygon, Binance Smart Chain, PancakeSwap, Uniswap v2, OpenZeppelin, ProxyContract, Alpaca Finance, EIP-721, ERC-20, GitHub.
PLAY2EARN GAME
04.2020 - 06.2021
Description: Web3.0 application with play2earn mechanics, which is on movement by car. Users owning a car earn standing in traffic, being behind the wheel while traveling, moving a car around the city. Each NFT car owner earns in-game currency, which can be used in-game or cashed in for profit.
Responsibilities:
- Blockchain development;
- Conducting security audits using RustSec to identify vulnerabilities and potential risks within dependencies and code;
- Writing and testing smart contracts using SPL;
- Development of dApp applications by integrating blockchain technology with gaming mechanics, including tokenomics and NFT assets;
- Specify and implement consensus mechanism;
- Developing and optimizing system components for transmitting and receiving payments;
- Customize transaction execution;
- Optimize smart contracts for gas efficiency to minimize transaction costs for users;
- Conduct performance testing and benchmarking of blockchain transactions to ensure scalability;
- Build custom runtime upgrade mechanisms;
- Implementing utility tokens;
- Integrate off-chain data services to enhance gameplay experiences and provide real-time data for in-game events;
- Building custom metrics and monitoring systems;
- Functional test of blockchain;
- Solve security issues;
- Mentoring new developers;
- Code review.
Environment: Rust, JavaScript, TypeScript, RustSec, Cargo, AuditRust, Fuzz, Solana, Anchor, SPL, Raydium, GitHub.