Jonathan Ballona Sanchez

Software Engineer from Bay Area, CA

I build fast, break fast, fix fast, ship fast. Cracked engineer who lives to learn.

Hero Picture of Jonathan Ballona Sanchez

Skills

Headstarter AI Logo

Jul 2024 - Feb 2025

Software Engineering Resident

Headstarter AI

• Crafted and deployed 5+ AI apps using RAG, OpenAI, Pinecone, and Stripe, achieving 98% accuracy with 450+ total users

• Developed a support agent with RAG, OpenAI, and Pinecone, handling 1,000+ queries weekly, boosting accuracy by 40%

• Led a team of 4 engineers using MVC patterns and agile, dedicating 60+ hours to complete 14 projects in 2-week sprints

Pixeland Technologies Inc Logo

Jul 2024 - Sep 2024

Software Engineering Intern

Pixeland Technologies Inc

• Created a scalable virtual office platform with React, Redux, and Firebase, boosting engagement by 30% across 10 teams

• Engineered real-time sync with Firebase, improving interactions for 2,000+ users with 20% reduced latency

• Developed WebRTC server with Express, optimizing video calls, cutting setup time by 30%, and supporting 500+ calls daily

Lob Logo

Feb 2024 - Apr 2024

Software Engineering Intern

Lob

• Implemented authentication system with React and Auth0, reducing unauthorized access by 3% for 10,000+ users

• Optimized PostgreSQL and ExpressJS queries, reducing response time by 50% for 5,000+ active users

• Enhanced React components and ExpressJS code, improving page load times by 15% for 7,500+ users

Sweep Logo

Jul 2023 - Dec 2023

Software Engineering Intern

Sweep

• Built automated document processing application with Docker and Flask, boosting efficiency by 40% for 1,000+ PDFs daily

• Integrated gpt-3.5 turbo powered virtual assistant for data insights, reducing errors by 20% in 3,000+ reviews weekly

• Devised a text compression algorithm, cutting file sizes by 30% and increasing speed by 40% for 2,000+ transfers daily

Open Avenues (Remix Labs) Logo

Jun 2023 - Aug 2023

Software Engineering Intern

Open Avenues (Remix Labs)

• Connected 5+ external APIs using the RemixBuilder no-code platform, unlocking access to over 10k data points weekly

• Automated data analysis tasks via RemixBuilder’s no-code interface, reducing manual report preparation time by 15%

• Implemented automated data validation rules with RemixBuilder’s tools, improving data accuracy by 30%

Featured Projects

VALLM Dash

VALLM

LLM Evaluation on real web content

Vallm.chat home

Vallm.chat

Multi-model chat/conversation branching

Recent Posts

Building Server-Side API Key Encryption with Convex and Node.js Crypto

A production-ready guide to securely encrypting user provided API keys with per user AES-256-GCM encryption and scrypt key derivation using Convex and Node.js—without ever storing plaintext secrets.

Jan 2026

Evaluating LLM Responses with RAG and DeepEval

Built a scalable API for evaluation 6+ LLM responses based off of scraped content

Apr 2025