Smart Contract Developer · Open to Remote

📧 bhanujangid0212@gmail.com · 🐙 github.com/ChapuKosi · 🐦 @_bhanujangid · 📍 India

Solidity developer focused on protocol and DeFi infrastructure, building independently since May 2024. Delivered three end-to-end projects: a gas-optimized constant-product AMM with flash swap support and 128K-iteration fuzz testing, a UUPS upgradeable vault with namespaced storage and full upgrade lifecycle coverage, and a multi-contract escrow marketplace with dispute resolution and 35 passing tests. Strong grasp of invariant reasoning, storage layout safety, and upgrade security. Open to remote roles in DeFi protocol development or smart contract engineering.

Gas-optimized Uniswap V2-style constant-product AMM — Solidity 0.8.30, Foundry — Deployed on Sepolia

• Implemented swap, mint, burn, and flash swap logic; enforces x*y≥k invariant with 0.3% fee adjustment
• Packed two uint112 reserves into a single storage slot (~5,000 gas saved per update); enabled via-IR compilation to resolve stack-too-deep on swap()
• Applied reentrancy lock on all external entry points; minimum liquidity lock (1,000 LP tokens burned to address(0)) prevents price manipulation at bootstrap
• Wrote 10 unit tests + 2 invariant tests (256 rounds × 500 calls = 128,000 fuzzing iterations) verifying k never decreases and reserves always match balances — 86.25% coverage, 92.39% on main contract

Deployed (Sepolia): AMMPair · Token0 · Token1

UUPS upgradeable ERC20 vault with namespaced storage — Solidity 0.8.30, Foundry, OpenZeppelin — Deployed on Sepolia

• Isolated vault state under a keccak256("fee.vault.storage.v1") namespaced slot, preventing collisions with ERC1967 proxy metadata and inherited contract storage
• Built V1 (basic deposit/withdraw) → V2 upgrade path adding configurable withdrawal delays, per-transaction limits, and pause mechanism; V2 strictly appends fields to preserve slot alignment
• Used reinitializer(2) to ensure V2 init runs exactly once post-upgrade; owner-only _authorizeUpgrade() blocks unauthorized upgrades — verified by test
• 7-test upgrade lifecycle suite validates state continuity (balances & owner preserved), V2 restriction enforcement, and unauthorized upgrade rejection

Deployed (Sepolia): Proxy · V1 Implementation · V2 Implementation — live V1→V2 upgrade on-chain

P2P escrow system with arbitration — 4 contracts, Solidity 0.8.20, OpenZeppelin — Deployed on Sepolia

• Factory pattern deploys isolated Escrow.sol instances; 6-state machine (Created → Accepted → Completed / Disputed → Resolved [Buyer/Seller/Split]) with strict transition guards
• Supports ETH and ERC20 payments via SafeERC20; ArbitratorRegistry manages reputation-based arbitrator pool with configurable fees and automatic deactivation for inactivity
• Gas-optimized with custom errors, immutable variables, struct packing, and event-over-storage pattern — ~25% aggregate gas reduction; circuit breaker pause on factory
• 35 tests across Escrow.t.sol (18) and EscrowFactory.t.sol (17); 100% pass rate covering all state transitions, access control, timelock claims, and edge cases

Deployed (Sepolia): EscrowFactory · ArbitratorRegistry · MockUSDC · MockDAI

Cyfrin Updraft — Structured Web3 developer program covering DeFi protocols, smart contract security, and advanced testing · 2024–2025

• Completed Uniswap V2 & V3 deep dives, advanced Foundry testing & fuzzing, and smart contract security fundamentals — applied directly in all three portfolio projects
• Additional coursework in ZK proof basics and Noir circuits, EVM assembly, and Rust

Independent Development · May 2024 – Present

• All three projects designed and owned end-to-end: architecture, design decisions, invariant reasoning, and test strategy driven independently — with AI tooling used for implementation assistance
• Reference implementations studied: Uniswap V2 core contracts and OpenZeppelin upgradeable libraries, used to inform — not copy — implementation choices
• All work public on GitHub with CI pipelines configured on all three repositories