Part of the Web3: Junior to Senior track · course 3 of 3
Production dApps: Security, Architecture & the Frontier
The senior tier of the Web3 track, continuing Smart Contracts with Solidity. Production on-chain work is a different discipline: code is immutable, money is adversarial, and every mistake is public. You reproduce the exploits that defined the industry and the patterns that prevent them, design a real dApp with wallet connection, RPC reads and an event indexer, then work through gas optimisation, upgradeable proxies and the move to L2s like Base. You read a live Uniswap pool and derive a swap quote from the constant-product formula, and finish at the 2026 frontier: account abstraction, passkey wallets, paymasters, and EIP-7702 delegations, with a live example of one on mainnet.
5 lessons · ~2.5 hours
Try the first lesson free, no account needed
Security: the exploits that defined the industry. The rest of the course unlocks with a free account.
1. Shipping on Chain
Security: the exploits that defined the industry
Reentrancy drained The DAO, a missing modifier froze Parity, and oracle manipulation still empties pools today. Reproduce the attack, then apply the pattern that stops it.
dApp architecture: wallets, reads, writes & indexers
A dApp is a normal web app with three unusual data paths. Reads go to an RPC, writes go through the user's wallet, and anything list-shaped comes from an indexer built on events.
Gas, upgradeability & L2s
Storage packing and calldata discipline cut gas. Proxies let you upgrade immutable code by separating storage from logic. Rollups make both matter less by moving execution off mainnet.
DeFi mechanics: how a swap actually settles
An automated market maker is two reserves and one equation. Read a live Uniswap pool, quote a swap from x·y = k, and see where slippage, fees and MEV come from.
Account abstraction & the frontier
Seed phrases and gas are the reason your parents are not on-chain. Smart accounts, paymasters and EIP-7702 remove both, and you can read a live delegation off mainnet today.