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Smart Contracts and NFT Infrastructure at Ex Populus (XAI)

Senior Solidity & Full-Stack Engineer · Ex Populus / XAI · 2023 – 2024
Solidity UUPS Proxy Foundry Hardhat The Graph (GraphQL subgraphs) Next.js / React Wagmi / Viem TypeScript Node.js

The role

At Ex Populus, the studio behind the XAI layer-3 network, I worked as a Senior Solidity and Full-Stack Engineer across the entire Web3 stack: smart contracts, on-chain indexing, front-end, and the NFT systems the ecosystem ran on. XAI sells the right to help secure its network as NFT “license keys,” and a lot of my work lived around those keys and the contracts behind them.

Tiny Keys: splitting live NFTs 100 to 1

The marquee project was an epic called Tiny Keys. The license keys had launched on a rising price curve, and by the time a key cost four or five thousand dollars, new buyers had dried up. The fix was a kind of stock split for NFTs: every existing holder was airdropped ninety-nine additional keys, and the price was divided by a hundred, so a $5,000 key became a $50 key and everyone who already owned one was made whole.

I wrote the smart-contract upgrades that executed it: changing the economics of contracts that were already live and holding real value, without breaking a single holder. That meant UUPS upgradeable Solidity contracts, careful attention to storage layout, and Foundry and Hardhat coverage of the upgrade path itself before anything touched mainnet.

Indexing and the dashboard

  • GraphQL subgraphs (The Graph): I built subgraphs to index on-chain events, giving the front-end real-time, queryable access to state without hammering RPC.
  • Front-end: I developed the React / Next.js dashboard, wired to the chain with Wagmi / Viem, so users got a polished, responsive view of their holdings.
  • Off-chain services: TypeScript / Node.js glue tying the on-chain and off-chain systems together.

NFT collections and marketplace

Beyond the keys, I launched NFT collections with other creators and built the marketplace they sold on. Across all of this work, the on-chain systems I helped build and ship handled more than $10M in value.

Stack

Solidity · UUPS upgradeable proxies · Foundry · Hardhat · The Graph (GraphQL subgraphs) · Next.js / React · Wagmi / Viem · TypeScript · Node.js