name: Wilfredo Rujel
location: Lima, Peru
company: SAP
role: Senior Software Engineer
interests:
- Building scalable web applications
- Competitive programming & algorithms
- Open source contributions
currently:
- Writing technical blog posts at wrujel.com/blog
- Building developer tools & side projects
leetcode-ui Personal LeetCode progress dashboard built with Astro 5, React 19, and Tailwi... ⭐ 0 • 🍴 0 • 
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portfolio Personal developer portfolio built with Next.js 16, TypeScript, and Tailwind ... ⭐ 0 • 🍴 0 •
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blog A developer blog built with Next.js 16, featuring file-based MDX content powe... ⭐ 0 • 🍴 0 • 
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webpage-gpt This is a fully responsive web page, built with React and deployed on Vercel. ⭐ 0 • 🍴 0 • 
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admin-dashboard-next Admin Dashboard built with Next 14, React 18, and TypeScript. ⭐ 0 • 🍴 0 •
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django-crud-react This project is a simple REST API with Django and React. ⭐ 2 • 🍴 0 • 
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Async Concurrency Control in Node.js: Semaphores, Throttling, and Backpressure Unbounded Promise.all is a silent OOM killer — here's how to build semaphores, t… |
📅 May 30, 2026backend⏱ 4 min read |
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The Transactional Outbox Pattern: Solving Dual-Write in Distributed Systems How the transactional outbox pattern eliminates the dual-write problem and guara… |
📅 May 16, 2026architecture⏱ 5 min read |
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Request Context Without Prop Drilling: AsyncLocalStorage in Node.js Use AsyncLocalStorage to propagate request-scoped context — trace IDs, user sess… |
📅 May 9, 2026backend⏱ 4 min read |
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TypeScript Branded Types: Compile-Time Domain Modeling Eliminate a whole class of runtime bugs by teaching TypeScript's type system the… |
📅 May 2, 2026engineering⏱ 5 min read |
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Contract-First API Design with OpenAPI and TypeScript Stop letting your API spec drift from your implementation — define the contract… |
📅 Apr 25, 2026backend⏱ 4 min read |
3921 problems solved | 6 languages | 72 topics | 57% avg acceptance
| Difficulty | Solved | Progress |
|---|---|---|
| 🟢 Easy | 944/944 | ████████████████████ 100.0% |
| 🟡 Medium | 2048/2050 | ████████████████████ 99.9% |
| 🔴 Hard | 929/930 | ████████████████████ 99.9% |
| Language | Problems | Share |
|---|---|---|
| 3456 | 88% | |
 Pandas | 235 | 6% |
| 103 | 3% | |
| 67 | 2% | |
| 56 | 1% |
