Smart Contracts in Practice: Building GigX

GigX is a decentralized freelance marketplace where smart contracts handle escrow, dispute resolution, and payment release. No intermediary. No platform taking 20%. Trustless by design.

The Core Escrow Contract

The central mechanic: client deposits ETH, freelancer delivers work, client approves, funds release. Disputes go to a 2-of-3 arbiter vote.

The key security lesson: always update state before making external calls (checks-effects-interactions pattern). Re-entrancy attacks exploit contracts that transfer funds before marking a transaction complete.

Gas Costs: The Real UX Killer

Creating a gig costs ~80,000 gas. At 20 gwei with ETH at $3000, that is $4.80 per transaction — nearly 10% overhead on a $50 gig, worse than Upwork.

The solution: Layer 2. Deploying to Polygon reduced costs by ~100x. For any consumer-facing dApp, mainnet Ethereum is the wrong environment. Start on Arbitrum, Polygon, or Base.

Dispute Resolution Without an Oracle

Pure on-chain work verification requires an oracle, which reintroduces centralized trust. GigX uses a 2-of-3 multi-signature scheme: any two of client, freelancer, and platform arbiter agreeing releases funds. Simple, effective, auditable.

Frontend: Wagmi v2 + Viem

Wagmi v2 is the correct Web3 React stack in 2025. Type-safe, hooks-based, handles wallet state and transaction lifecycle without the ceremony of ethers.js or web3.js.

What I Would Do Differently

Start on L2 immediately. Use TheGraph for event indexing from day one. Keep only trust-critical logic on-chain. Run Slither static analysis before any deployment touching real value.

The blockchain constraint forces you to think about trust at a systems level in a way nothing else does.

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*GigX is pinned on GitHub (AppXcess-GigX). Contracts deployed on Sepolia testnet.*