Wallet Hawk

About

Enter an Ethereum wallet address and see its full token transaction history across ERC-20, ERC-721 and ERC-1155 — largely NFT assets — aggregated from the OpenSea and Etherscan APIs.

It arrived as a rough Express, EJS and jQuery application. I rebuilt it completely.

What I built

• Rebuilt the application in Laravel with Inertia.js and React, including a redesigned frontend.
• Engineered around hostile upstream rate limits — shared across every user of the product — with database caching of fetched transactions, application-level rate limiting, atomic locks to stop duplicate in-flight requests, and a queue system to keep external calls to a minimum and avoid suspension.

Outcome

Delivered and paid. Late-stage requirement changes made the closing phase difficult.

What I took away

• When the external API is the bottleneck, caching strategy becomes the architecture. Everything else follows from how few calls you can get away with.
• Atomic locks solved a problem I did not anticipate: concurrent users requesting the same wallet and multiplying the API cost of a single result.
• Scope needs to be pinned down in writing before the last mile, not during it.