Humberto Yusta

Developed and tested a multi-tenant SaaS with an AI agent framework focused on customer support, an omnichannel inbox, and CRM management. Built agent memory from generated and uploaded documents using parsing, indexing, and vector retrieval. Built a resilient agent scheduler with reminders, recurring tasks, retries, recovery, and monitoring.

Software Engineer at Flexus (2025-09 – Present)

• Developed and tested a multi-tenant SaaS with an AI agent framework focused on customer support, an omnichannel inbox, and CRM management.
• Built agent memory from generated and uploaded documents using parsing, indexing, and vector retrieval.
• Built a resilient agent scheduler with reminders, recurring tasks, retries, recovery, and monitoring.
• Integrated WhatsApp, Telegram, and a web chat widget into an omnichannel inbox, enabling human support and providing AI agents with session-based context.
• Optimized PostgreSQL queries, transactions, indexes, and triggers, and built Redis-backed GraphQL subscriptions for efficient real-time updates.

Software Engineer at Refact.ai (2024-09 – 2025-09)

• Built an open-source coding agent in Rust with code chat, completion, and Docker, shell, and MCP integrations.
• Optimized the agent for SWE-bench, ranking 2nd on Verified and 1st on Multimodal and Lite at submission time, with a higher Pass@1 than OpenAI Codex, while also ranking 1st on Aider Polyglot Benchmark.
• Improved RAG result quality and performance over a local codebase and library knowledge base.
• Built an isolation system to run agents in Docker, with checkpoints using a shadow Git.
• Optimized file search, parsing, AST construction, and I/O across Windows and Unix systems.
• Debugged and refactored async code, eliminating deadlocks and reducing runtime and memory usage.

Lead Developer at Harbour Space (2024-03 – 2025-08)

• Led a team of four in developing and maintaining the university's website, admissions, and academic platforms.
• Enhanced and maintained a Laravel backend with ActiveCampaign and Google API integrations.
• Managed PostgreSQL and MySQL databases in Docker, using indexes for optimization and setting up backups.
• Optimized DigitalOcean infrastructure, achieving: A 30% cost reduction.
• Improved data durability and availability with object storage for media files.
• Enhanced monitoring with DigitalOcean tools, reducing downtime.

Software Developer at Harbour Space (2023-10 – 2024-03)

• Full-stack developer for the university's admissions and academic platforms using Laravel and Next.js.
• Increased deployment frequency by 60% with new CI/CD pipelines using GitLab and Docker.
• Set up monitoring and user activity tracking, cutting error-resolution time from 3 to 1 day.
• Managed a data warehouse, ingestion scripts, and dashboards with BigQuery and Looker Studio.

Software Developer at Leagues of Code (2022-09 – 2023-10)

• Full-stack developer for a programming e-learning platform.
• Developed and tested Laravel back-end services with a GraphQL API, increasing test coverage from 50% to 80%.
• Built and tested React and Next.js projects, reducing page-load times by 40%
• Maintained and tested an online judge with Python, Flask, RabbitMQ, and Celery
• Built and maintained CI/CD pipelines using GitLab and Docker

Software Developer at XETID (2021-09 – 2022-08)

• Back-end developer for a ticketing site.
• Optimized PostgreSQL with constraints and indexes.
• Optimized NGINX configurations, improving page-load performance by 200%.

Programming Teacher at Leagues of Code (2022-09 – 2023-07)

• Taught competitive programming in C++ to 25 students for 6 months
• Taught introduction to programming in Python to more than 60 students at St. Paul's School for 7 months
• Taught a 30-hour introduction to Python course to 20 students.

BSc. in Computer and Data Science – Harbour Space University

BSc. in Computer Science – University "Marta Abreu" of Las Villas