Karel Senior Backend Engineer

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Senior Software Engineer

TVUP Streaming Media

Jun 2025 - Mar 2026 (10 months)

• Reduced MongoDB aggregation latency by 83% (600ms to 100ms) by consolidating 5 queries into a single pipeline,
eliminating 164,900 unnecessary document scans per request and significantly reducing infrastructure costs
• Set up shared ESLint/Prettier configs, reduced style discussions in PRs, made reviews faster
Introduced modern development workflows including pair programming, lazygit, atuin, and Al-assisted tools (Context7
MCP, spec-driven development), helped the team move faster
• Built custom invoicing automation system that eliminated manual administrative overhead for remote team members

Senior Backend Developer

Fz Sports

Feb 2021 - Jun 2025 (4 years 5 months)

• Built 'Wilson', a NestJS API with refine.dev dashboard that replaced brittle spreadsheet-and-XML workflows with vali-
dated forms, real-time updates, and full audit trails for tournament and live video operations
• Built API endpoints integrating AWS SDK that enabled video team to programmatically create MediaConnect flows and
MediaLive workflows, cutting event setup time from hours to minutes
• Go-to person for production issues, debugging, and architecture decisions
• Mentored junior developers and established best practices for testing, code review, and documentation

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Back-end Developer

AG Software S.A

Jun 2019 - Feb 2021 (1 year 9 months)

• Led Rails 4 to 5 upgrade for AgNegocio ERP platform used by Nicaraguan businesses, no breaking changes, backward
compatible with existing customer data
• Refactored core inventory movement concern to handle updates, deletions, and restores while maintaining accurate
stock levels across all transaction types
• Optimized complex PostgreSQL queries for enterprise cash flow and business analytics reports, eliminating timeouts
on large datasets
• Mentored 3 developers, improving team code quality and reducing review cycles
• Introduced RuboCop with standardized patterns for helpers, presenters, and decorators

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Teaching Assistant

CS50xni (Harvard CS50 Nicaragua)

Apr 2019 - Jan 2022 (2 years 10 months)

• Teaching Assistant for Harvard's CS50 Computer Science course adapted by Fundación UNO, supporting 50+ students
annually
• Used Socratic method to guide students through C, Python, and JavaScript fundamentals; developed mentoring skills
still applied with junior developers

Karel

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