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... β 0 β’ π΄ 0 β’ 
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portfolio Personal developer portfolio built with Next.js 16, TypeScript, and Tailwind ... β 0 β’ π΄ 0 β’
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blog A developer blog built with Next.js 16, featuring file-based MDX content powe... β 0 β’ π΄ 0 β’ 
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webpage-gpt This is a fully responsive web page, built with React and deployed on Vercel. β 0 β’ π΄ 0 β’ 
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admin-dashboard-next Admin Dashboard built with Next 14, React 18, and TypeScript. β 0 β’ π΄ 0 β’
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django-crud-react This project is a simple REST API with Django and React. β 2 β’ π΄ 0 β’ 
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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⦠|
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May 30, 2026backendβ± 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⦠|
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May 16, 2026architectureβ± 5 min read |
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Request Context Without Prop Drilling: AsyncLocalStorage in Node.js Use AsyncLocalStorage to propagate request-scoped context β trace IDs, user sessβ¦ |
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May 9, 2026backendβ± 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⦠|
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May 2, 2026engineeringβ± 5 min read |
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Contract-First API Design with OpenAPI and TypeScript Stop letting your API spec drift from your implementation β define the contractβ¦ |
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Apr 25, 2026backendβ± 4 min read |
3921 problems solved | 6 languages | 72 topics | 57% avg acceptance
| Difficulty | Solved | Progress |
|---|---|---|
| π’ Easy | 944/944 | ββββββββββββββββββββ 100.0% |
| π‘ Medium | 2048/2050 | ββββββββββββββββββββ 99.9% |
| π΄ Hard | 929/930 | ββββββββββββββββββββ 99.9% |
| Language | Problems | Share |
|---|---|---|
 Rust | 3456 | 88% |
 Pandas | 235 | 6% |
 Sql | 103 | 3% |
 Typescript | 67 | 2% |
 Cpp | 56 | 1% |
