Solidity Developer · Foundry · Security-focused
_{Remote · GMT+3 · Available 30+ hrs / week · Open to contract & full-time}

Solidity developer building access-controlled smart contracts with full Foundry test coverage — including fuzz and invariant tests, not only unit. Security-mindset from architecture to commits: CEI pattern, custom errors, role separation, OpenZeppelin primitives.

Code-first portfolio — every project below is open for review.

Production-style marketplace system in Solidity (815+ lines across 3 contracts communicating through interfaces). Strict on-chain accounting with inventory, order lifecycle and fee orchestration.

• Three-contract architecture — Inventory + OrderRegistry + MarketPlace, isolated via interfaces
• MarketPlace — configurable BPS fees, VIP seller discounts, VIP buyer cashback, promo codes, pull payments
• Accounting invariant verified by handler-based invariant tests with ghost variables: contract balance == userBalances + platformBalance
• Reserve / release / finalize pattern for safe item locking, packed Item struct (uint128 + uint128 + bool)
• State machines — Inventory: Active / Frozen / Closed; Order: Created → Paid → Shipped / Cancelled
• Static analysis with Slither

Stack: Solidity ^0.8.29 · Foundry · OpenZeppelin · Slither

Uniswap-V2-style AMM in Solidity / Foundry — built from scratch.

• LiquidityPool — constant-product curve, MINIMUM_LIQUIDITY burn pattern, ReentrancyGuard, SafeERC20
• Swap implemented and verified by fuzz test asserting k = x * y constant-product invariant holds after every trade
• PoolFactory.createPool for paired tokens
• ERC-20 LP token (OpenZeppelin), geometric-mean initial mint, proportional subsequent mints
• Currently expanding: Router (multi-hop), fee mechanism, price oracle / TWAP

Stack: Solidity ^0.8.29 · Foundry · OpenZeppelin

Solidity        ^0.8.29
Framework       Foundry — Forge, Cast, Anvil
Libraries       OpenZeppelin — ERC-20, ERC-721, ReentrancyGuard, SafeERC20, AccessControl
Security        CEI, custom errors, RBAC, state machines, packed structs, pull payments
Testing         Foundry — unit, fuzz, invariant
Tooling         Git · Conventional Commits · GitHub Actions · ethers.js · Python

• Token contracts — ERC-20 / ERC-721 with custom logic
• Vesting, staking, airdrop systems
• Access control & role-based contract architecture
• State-machine and lifecycle-driven systems
• Foundry test design — unit, fuzz, invariant
• Solidity refactoring & modernization (custom errors, OZ v5)

• 📨 Email: 0xkiko.dev@gmail.com
• 💬 Telegram: @engineer_web3

_{Languages: English (fluent, async-friendly) · Russian (native)}