Elliott Alexander

01 About

02 Side projects

Things I've built on my own time

• Claude Code Session Explorer

  Published as CCExplorer, an open-source npm tool that measures whether a skill or MCP server is actually steering the agent well. It shows context composition, token cost, and where an integration helps versus bloats.

  GitHub ↗ npm ↗

• Human-in-the-Loop Transaction Approval

  Published as request-wallet-sign, an open-source npx utility and Agent Skill that lets an AI agent hand a fully-formed transaction to its owner for review and approval in a local browser wallet. The agent never holds a private key.

  GitHub ↗ npm ↗

• How Was My Wallet Hacked?

  A web app for crypto-wallet hack victims. It walks through a guided diagnostic to figure out how the wallet was likely compromised, then covers the opsec needed to stop it happening again.

  Website ↗ GitHub ↗

03 Experience

Where I've worked

1. Ethereum Foundation June 2025 – June 2026
   Developer Experience Engineer

   TypeScript · Solidity · Next.js · Agent Skills · Context Engineering

   • Helped build ethskills.com, a library of Agent Skills that give LLMs the context to build correctly on Ethereum. Authored skills targeting the hardest gaps for coding agents, from missing domain knowledge to a default indifference to adversarial environments, encoding the threat-model reasoning they skip.
   • Built and maintained a curated repository of ecosystem tools and resources, and wired the official developer-facing pages to pull from it dynamically.
   • Helped drive the team’s strategic shift from “Developer Growth” to “Builder Growth,” repositioning the org around AI lowering the barrier to building on Ethereum.
   • Set the quality bar for Agent Skills across the organization, guiding other teams in bringing their collections up to standard, and pushed cross-team efforts to make tooling more discoverable for builders.
   • Oversaw the creation of three new Solidity challenges in the Speedrun Ethereum curriculum, covering Oracles, Over-collateralized Lending, and Stablecoins.
   • Taught Ethereum workshops at universities and conferences that took developers to their first deployed app.
2. BuidlGuidl Sep 2021 – Apr 2024 part-time, then full-time through June 2025
   Full Stack Software Developer

   TypeScript · JavaScript · Next.js (React) · Solidity · MongoDB

   • Led a team building the Ethereum Tech Tree, a medium-hard set of Solidity challenges.
   • Built HackedWalletRecovery.com, which lets non-technical users retrieve assets from a compromised wallet using Flashbots transaction bundles under the hood.
   • Created the Impact Calculator, a prototype for gauging the impact of retroactive public-goods funding that helped guide the Optimism Foundation toward metrics-based builder rewards.
   • Built a Scaffold-ETH 2 extension highlighting the Arbitrum ecosystem.
3. BitPay Feb 2022 – Apr 2024
   Back End Engineer

   TypeScript · Node.js · Solidity · MongoDB · Docker · Mocha

   • Primary focus on Bitcore, an open-source monorepo providing a standardized API across multiple blockchains; added Polygon support across internal tools and made the codebase more easily extendable to other EVM chains.
   • Updated and deployed a new Solidity invoicing smart contract to fix a bug blocking some ERC-20s; the prior contract had processed $470M in value. Added all supported ERC-20 token contracts to the test suite for precise testing.
   • Cut the data stored in the database on behalf of wallet users by 70% on EVM chains; built internal tools for replacing transactions on EVM and UTXO chains, plus an app validating internal accounting-ledger updates via a quorum of nodes.
4. DevNext Jan 2019 – Feb 2022
   Full Stack Software Developer

   TypeScript · JavaScript · Angular · C# · SQL

   • Maintained and improved dozens of applications: set up ETLs for business-data access, built an extensible cross-database audit-data viewer, and created tooling for non-technical users to build custom formulated queries.
   • Built a public-facing Angular app for volunteer-opportunity management, extended an email-campaign tool to support SMS, and helped establish team git best practices during a migration from TFS.

04 Skills

Tools & focus areas