Elliott Alexander

01 About

02 Side projects

Things I've built on my own time

• Claude Code Session Explorer

  Published as CCExplorer, an npx tool that analyzes Claude Code sessions to measure whether a skill or MCP server is steering the agent effectively, surfacing context composition, the token cost an integration adds, and where it helps versus bloats. A data-driven way to optimize AI coding-agent performance.

  GitHub ★ 9 ↗ 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 to review and approve in a local browser wallet, so the agent never holds a private key. Security-first design that coding agents can invoke directly.

  GitHub ↗ npm ↗

• How Was My Wallet Hacked?

  Walks crypto-wallet hack victims through a guided 15–20 question diagnostic to pinpoint how their wallet was most likely compromised, then teaches the security practices to prevent a repeat.

  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 · LLM tooling

   • Built and shipped AI-assisted developer tooling, co-creating ethskills.com, an open-source library of ~20 Agent Skills that gives coding agents the context and guardrails they need to build accurately in a complex, high-stakes domain, measurably improving how reliably AI agents generate working applications.
   • Set and enforced the organization-wide quality bar for Agent Skills, partnering with three teams to bring their Skill collections up to standard and leading cross-team efforts to make developer tooling more discoverable, technical leadership across teams without a management title.
   • Championed an AI-first strategy for the team, influencing the organization to adopt AI tooling as the primary lever for lowering barriers to entry for developers and shaping roadmap priorities accordingly.
   • Established authoritative public documentation on emerging development patterns, improving the quality of knowledge sources relied on by both engineers and AI models across the ecosystem.
   • Created three new advanced Solidity challenges (Oracles, Over-collateralized Lending, Stablecoins) for the Speedrun Ethereum curriculum (10,000+ developers) and refreshed the existing core challenges, including Tokenization, the introductory challenge with 5,500+ completions.
   • Taught 8 hands-on developer workshops to audiences of 15–80 worldwide, including the Universities of Cambridge and Waterloo, taking developers from zero to their first deployed application.
2. BuidlGuidl Sep 2021 – Apr 2024 part-time, then full-time through June 2025
   Full Stack Software Developer

   TypeScript · JavaScript · Next.js · Solidity · MongoDB

   • Led a team building the Ethereum Tech Tree, a structured set of intermediate-to-advanced Solidity challenges that gives developers a guided path to mastering smart-contract development.
   • Designed and built HackedWalletRecovery.com, a tool that lets non-technical users rescue assets from a compromised wallet, submitting the recovery transactions privately so attackers’ automated bots can’t intercept the funds first. Now behind hundreds of successful recoveries, it turns an expert-only, high-stakes process into a guided self-serve flow.
   • Created the Impact Calculator, a prototype that scored the real-world impact of open-source projects so funding could be awarded on results, helping shift the Optimism Foundation toward data-driven grant decisions.
3. BitPay Feb 2022 – Apr 2024
   Back End Engineer

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

   • Shipped a new Solidity invoicing smart contract that fixed a bug blocking certain token (ERC-20) payments, on a payment contract that had processed $470M in transaction value, and added every supported token to the test suite for precise, regression-proof coverage.
   • Reduced wallet-supporting database storage by 70% across multiple blockchains, cutting infrastructure cost and improving performance.
   • Core contributor to Bitcore, the open-source monorepo providing a standardized payments API across multiple blockchains; added Polygon support and refactored the codebase so new chains could be integrated with far less engineering effort.
   • Strengthened the reliability of core payment infrastructure: built tooling to recover stuck transactions across different blockchain architectures, plus a ledger-validation service that required agreement across multiple independent nodes to keep corrupted data out of financial records.
4. Devnext Jan 2019 – Feb 2022
   Full Stack Software Developer

   TypeScript · JavaScript · Angular · C# · SQL

   • Built self-serve tooling that let non-technical staff create custom database queries without engineering assistance, eliminating a recurring bottleneck that had tied up engineers on ad-hoc data requests.
   • Maintained and improved dozens of business applications, building ETL pipelines that gave teams direct access to business data and a cross-database audit viewer that gave the team one place to trace data across previously siloed systems.
   • Shipped a public-facing Angular app that streamlined how an organization recruited and coordinated volunteers, and extended its email-campaign platform with SMS to reach supporters on a new channel.
   • Drove the team’s migration from TFS to Git, establishing the branching and code-review practices that cut release risk and improved day-to-day collaboration.

04 Skills

Tools & focus areas