Web3 work

My contribution

197 of 242 commits on the web application, and the whole of the workers service, 33 commits out of 33. Two other developers contributed to the web application.

What I built

• Minting flow for an identity NFT on Solana: the transaction is built server side, signed in the browser through the wallet adapter, then confirmed and recorded.
• Wallet connection with Phantom, Solflare and Backpack, with a guard that keeps the connected wallet and the authenticated account in step.
• Authentication with Privy and JWT verification on the protected routes, combined with GitHub and X account linking through OAuth.
• Score interface: leaderboard, radar chart of the score attributes, referral section and public profile sharing.
• Access control by invitation code, an admin area, CSRF tokens and security headers.

The hard part

The score is computed from several external sources and none of them answers quickly. I moved that work out of the request cycle into four asynchronous Python workers behind a Redis queue, one per source, writing to PostgreSQL. The interface had to stay usable while a score was still being computed, so each source carries its own pending, done and failed state instead of one global spinner. Halfway through, the data layer also moved from Supabase to PostgreSQL on Railway.

Stack

Next.js 13 App Router, TypeScript, Tailwind, shadcn/ui, Solana web3.js, wallet adapter, Anchor, Privy, PostgreSQL, Redis, Python

My contribution

64 of 80 commits, as project lead and full stack developer, with two other contributors.

What I built

• Pet identity built on Decentralised Identifiers, so the record follows the animal rather than one vet or one owner.
• Wallet connection through the Crossmark SDK for the XRP Ledger, alongside Web3Auth so an owner with no crypto background can sign in socially and still end up with a wallet.
• Google sign-in, and the owner and veterinarian views on top of the identity record.

The hard part

The difficulty was the audience, not the ledger. Pet owners and vets do not have wallets, so the interface had to hide key management behind a social login while keeping the record genuinely self-sovereign.

Stack

Next.js, TypeScript, Crossmark SDK, Web3Auth, Google OAuth

My contribution

126 commits, the entire project: contracts and interface.

What I built

• Solidity contracts with Hardhat and OpenZeppelin: associations are registered, donations are traced, and funds reach the chosen association directly.
• Next.js interface with RainbowKit for the wallet connection, ethers and wagmi for reads and writes, and transaction states surfaced in the UI.
• A donor can follow what happened to a donation from the interface.

The hard part

This is where I learned to design the contract and the interface together: deciding what belongs on chain, what can be read back from events, and how to show someone a transaction that has been sent but not yet mined.

Stack

Solidity, Hardhat, OpenZeppelin, Next.js, RainbowKit, ethers, wagmi, Tailwind

My contribution

Both repositories are entirely mine: 29 commits on the web application, 12 on the mobile one.

What I built

• Next.js web application with Privy authentication, Solana web3.js to read the portfolio, and charts of the holdings.
• An assistant layer built on LangChain that comments on the portfolio, wired to a locally run model during development.
• A separate React Native application using the Solana Mobile Wallet Adapter, so the connection goes through the wallet already installed on the phone.

The hard part

Two different wallet connection models for the same product, one in the browser and one on mobile, where the phone hands control to another application and gives it back. Getting the user back into a coherent state after that round trip was most of the work.

Stack

Next.js, TypeScript, Solana web3.js, Solana Mobile Wallet Adapter, Privy, React Native, LangChain, Convex

My contribution

31 of 56 commits, on the Flutter application and the integration. The Circom circuit work was shared with teammates who specialise in zero-knowledge.

What I built

• Flutter application that generates an age proof and scans it as a QR code.
• A Groth16 proof verified by a contract on Arbitrum Sepolia.
• The user proves they are above an age threshold without revealing their date of birth.

The hard part

Proof generation is slow and happens on the phone, so the application had to stay honest about what it was doing rather than appear frozen.

Stack

Flutter, Dart, Circom, Groth16, Mopro, Arbitrum Sepolia