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Juan Pablo Masyk

@juanpablomasyk

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Software developer at Outlier (Scale AI), reviewing AI-generated code and building a ledger reconciliation MCP server.

Argentina

Message

At Outlier (Scale AI), I review AI-generated code in Java, JavaScript, TypeScript, SQL, and Python for correctness, edge cases, and specification adherence. I also design tasks for AI agents, analyze their trajectories, and conduct quality reviews.

I built ledger-mcp, an MCP server for querying and reconciling an accounts payable ledger, with read-only SQL safeguards and an evaluation suite. At Fullh4rd, I restructured a legacy database and optimized queries, and I developed a RESTful API in Kotlin for a freelance project.

Experience

Work history, roles, and key accomplishments

Current

AI Trainer / Quality Reviewer

Current

Outlier (Scale AI)

Nov 2024 - Present (1 year 11 months)

Review code generated by AI models in Java, JavaScript, TypeScript, SQL and Python for correctness, edge cases and adherence to specifications. Designed multi-step tasks for AI agents working through MCP tool servers, seeded test data with SQL, wrote golden solutions and weighted rubrics, and analyzed agent trajectories to calibrate difficulty.

Java JavaScript TypeScript SQL Python MCP Docker Linux Cursor Claude ChatGpt Grok Code Review Quality Assurance

Programmer

Fullh4rd

Jul 2024 - Jul 2025 (1 year)

Restructured a legacy database into a clean, consistent design, optimizing SQL queries and response times. Improved website performance and functionality using JavaScript, and resolved code conflicts and bugs to improve system stability.

SQL JavaScript Database Design Performance Optimization Debugging

RESTful API Development, Freelance Project

Freelance

Mar 2022 - Jul 2022 (4 months)

Developed a RESTful API in Kotlin, applying best practices for scalability and efficiency. Integrated the API with Firestore, ensuring secure data storage and optimized queries.

Kotlin REST APIs Firestore Scalability Efficiency

Personal Project, ledger-mcp

Personal Project

Oct 2026 - Present (0 months)

Built an MCP server that lets LLM agents query and reconcile an accounts payable ledger, including a read-only SQL tool with injection protection, invoice and payment matching, and a guided prompt for monthly close. Wrote an eval suite with reference answers, 26 pytest tests, a Docker image, and GitHub Actions CI.

Python MCP SQL Docker GitHub Actions Pytest LLM Evaluation Suites