Token Presale Platform with Tiered Pricing & Vesting

The summary

Built an end-to-end token presale platform with tiered pricing, Merkle whitelist, multi-currency support (ETH + USDC + USDT), and linear vesting with cliff. Deployed to mainnet, audited contracts, frontend integrated with multi-wallet UX.

The problem

• ▸Client needed a presale platform that could handle 5,000+ whitelisted buyers across 3 pricing tiers within a 72-hour launch window.
• ▸Previous attempt by another team used hardcoded gas-inefficient logic, failed pre-audit, and missed launch date.
• ▸Buyers needed multi-currency support (native ETH + 2 stablecoins) with seamless wallet UX.

The approach

1. 1.Three-contract architecture: Token (OpenZeppelin ERC-20), Presale (custom tier + buy logic), Vesting (linear with cliff). Separation made audit easier and lets vesting upgrade independently.
2. 2.Merkle proof whitelist instead of on-chain mapping — saved ~$80K in deployment gas for 5,000 addresses, and frontend builds proofs client-side.
3. 3.Tier transition logic that splits a buy across price tiers (e.g., buying 1000 tokens when tier 1 has 500 left at $0.10 means 500 at $0.10 and 500 at $0.15).
4. 4.Next.js 14 App Router frontend with Wagmi v2 + RainbowKit. Real-time tier preview, gas estimation, chain detection, slippage warnings.
5. 5.Pre-audit hardening pass: 25-point security checklist (reentrancy, decimal mismatch, front-running, refund precision). Third-party audit by Hashlock — passed with zero criticals.

Results

Tech stack

What surprised me

The split-across-tiers buy logic was the part 95% of amateur presales get wrong. Spending an extra 2 days on a clean state machine for tier transitions paid for itself when audit time came — the reviewer flagged zero issues in the buy path.