Олександр

Oleksandr Cheliadin
QA Engineer | Smart Contract Engineer

SUMMARY
QA Engineer with 1 year of hands-on testing experience and 3+ years of commercial experience in
software development, primarily in Web3 and blockchain products. Experienced in functional,
regression, integration, API, and exploratory testing, as well as requirements analysis and working
with test documentation. Strong technical background in smart contracts and Web3 provides a
deep understanding of application logic, APIs, blockchain transactions, and complex system
integrations. Detail-oriented, with a strong focus on identifying edge cases, analyzing system
behavior, and ensuring product quality.

WORK EXPERIENCE CONTACT
4IRE | 09.2025 - Current [open contact info](look above in the "contact info" section)

QA Responsibilities linkedin

Performed functional, regression, integration,
SKILLS
exploratory, and end-to-end testing of Web3 applications
across frontend, backend, and smart contract QA & Testing
components.
Manual Testing, Functional,
Analyzed requirements and business logic to identify Regression, Integration,
inconsistencies, missing scenarios, edge cases, and Exploratory, E2E, API Testing,
potential issues before release. Test Cases, Checklists, Bug
Reporting
Tested REST APIs, validating requests, responses, status
codes, error handling, authentication, and application Tools & Web
business logic. Postman, Jira, Chrome
Tested complex DeFi and RWA workflows, including wallet DevTools, REST API, HTTP,
interactions, blockchain transactions, JSON, GraphQL, SQL, Git
deposits/withdrawals, staking, orders, price feeds, fees,
Web3 & Development
and refunds.
Validated blockchain and indexed application data using Solidity, TypeScript,
JavaScript, Blockchain, DeFi,
The Graph and GraphQL, ensuring data consistency
Smart Contracts, The Graph,
between smart contracts and application components. Ethers.js, Hardhat, Foundry
Used browser DevTools to analyze network requests,
responses, console errors, and frontend/backend
integration issues.
LANGUAGES
Created test cases and checklists based on requirements,
business logic, and feature specifications. English — Intermediate
Identified and reported defects to developers, providing Ukrainian — Native
reproduction details, expected and actual behavior, and
supporting information for investigation.
Performed retesting and regression testing after fixes
and collaborated with frontend, backend, and blockchain
developers to investigate and resolve issues.

4IRE | 04.2023 - Current

Smart Contract Engineer | Blockchain Engineer

Key Responsibilities & Accomplishments:

Carbcoin — Carbon Credit Trading Platform
Designed and developed a decentralized bid/ask marketplace with partial fill support and
operator-executed order matching
Implemented an on-chain auction system with fractional bidding logic, sorted bid queues,
and partial execution capability
Built a platform contract managing carbon capture project registration, token
minting/burning lifecycle, and NFT certificate issuance

Stablecoin DeFi Protocol
Developed an upgradeable (UUPS) Vault contract integrating Chainlink price feeds for
multi-stablecoin deposits with automatic token minting and treasury management
Built an ERC4626-based staking contract with EIP-712 signed stake/unstake authorization,
non-transferable shares, and cooldown-based batch withdrawals
Implemented withdrawal request queuing with cooldown periods and batch claim
functionality

TrustLinq — Custodial Vault Infrastructure
Architected a factory-based vault deployment system using deterministic CREATE2 clones
for per-user proxy vaults
Implemented a multi-signature super admin governance system with proposal-based
admin rotation and expiry logic
Built whitelisted withdrawal and transfer controls with role-based access separation

Gold RWA Tokenization Platform
Built a WalletFactory system with per-order deterministic wallets (CREATE2), Chainlink
XAU/USD gold pricing, and multi-token payment support
Developed buy and sell order modules with TTL-based expiry, fee resolution, royalty
distribution, and overpayment refund logic
Implemented a minimal WalletImplementation clone for secure, factory-controlled ERC20
transfers

DAO Governance System
Developed a full on-chain DAO governance system with multi-stage motion lifecycle: team
lead review → Nexus team voting → lazy consensus → commit-reveal public voting →
cooling off
Implemented reputation-based voting power with token locking mechanics tied to
proposal duration
Built a factory-based clone deployment system for DAOs, teams, and reputation tokens
with role-based access control