Tools I build for developers
Interfaces for AI coding agents, from a terminal UI to a native macOS app and a fast local AI engine.
Distill
Coding-agent harness and terminal UI that gets far more done with far fewer tokens. Works with Grok, Codex and any OpenAI-compatible model. UltraSave mode cost 93% less on a 20-task benchmark, with every task passing.
github.com/samuelfaj/distill
MacCode
Native macOS development cockpit: agents, terminals, SSH, browser, files and git in one split-pane workspace. Layouts persist across launches, and the whole workspace can be driven from an iPhone.
github.com/samuelfaj/MacCodeLightning MLX
Fast local AI engine for Apple Silicon, tuned for agentic use. Over 2× the decode speed of mlx-lm on Qwen3.6 models.
github.com/samuelfaj/lightning-mlxDevelopment Harness
Software engineering with AI agents, from the first contract to production.
A field guide for designing, constraining and verifying AI agents in real software systems, with practical workflows, safety gates and enterprise operations.
Where I've shipped
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Nov 2023 – PresentNew York · remote
SecurityScorecard · Senior Software Engineer
Full-stack engineer at a 400+ person cybersecurity company, split evenly between the UI and the services behind it.
- Cut the bundle size by 90%, making the app load 8× faster.
- Build scalable React/TypeScript codebases and lead UI/UX improvements in usability and accessibility.
- Removed duplicate requests across the system, lowering server load and making the UI more responsive.
- Ship features end to end with designers and product managers, covered by Playwright and Cypress tests.
ReactTypeScriptRedux / React QueryNode.jsAWSTerraformPlaywrightCypress -
Dec 2022 – Nov 2023New York · remote
Mahisoft Inc · Senior Software Engineer
Lead engineer for Top Trader League, turning board-level direction into shipped product.
- Built responsive, user-friendly React interfaces on top of backend systems I designed.
- Added asynchronous messaging, which reduced database overload.
- Moved the platform to serverless on Google Cloud for scale at lower cost.
ReactRedux / React QueryNode.jsPHP (Laravel)Google CloudAWSTerraform -
Aug 2021 – Dec 2022Brazil
Vagalume Mídia · Senior Software Engineer
Full-stack and DevOps work on one of Brazil's largest music sites, at very high traffic.
- Rebuilt Vagalume Radios in Node.js from scratch, improving performance and cutting AWS costs.
- Shipped frontend work in React and Vue.js; learned high-scale AWS infrastructure from a top AWS expert.
ReactVue.jsNode.jsPHPAWSTerraform -
Sep 2019 – Aug 2021Brazil
Secretária Virtual · Senior Software Engineer
Led technology across a portfolio of companies, owning development process as well as code.
- Architected business-critical systems, infrastructure, monitoring and testing.
- Introduced cloud computing, continuous integration and Scrum.
AngularJSIonicNode.jsPHPLaravelCodeIgniter -
Feb 2019 – Dec 2021Side project
Anilha · Founder
Designed and built a mobile app for flexible diet and workout tracking, from the UI to the serverless backend.
IonicAngularNode.jsAWS LambdaDynamoDBTerraform -
Sep 2017 – Sep 2019Brazil
E-Trust · Senior Software Engineer
Information-security company serving some of Brazil's largest banks and corporations.
- Redesigned the Horacius system's frontend while keeping it compatible with legacy systems; well received by enterprise clients.
- Set clean-code (OOP) standards and continuous integration with automated migrations and code checks.
PHPMicrosoft SQL ServerWindows Server
One engineer. The whole product.
Hire me for a feature and you get all of it: the interface users touch, the API behind it, the cloud it runs on and the AI that makes it smarter. I ship it, measure it and keep it fast.
Interfaces people enjoy using
Cut SecurityScorecard's bundle by 90%, making the app load 8× faster.
React · TypeScript · Redux · React Query · Vue.js · Angular · Ionic · design systems · accessibility
AI that ships, not demos
Distill: 800+ stars and 93% lower cost on a 20-task agent benchmark, every task passing.
LLM products · coding agents · agent harnesses · local inference (MLX)
Backends that hold under traffic
Rebuilt Vagalume Radios in Node.js for one of Brazil's largest music sites, cutting AWS costs.
Node.js · PHP · Laravel · REST APIs · asynchronous messaging
Infrastructure that costs less
Moved Top Trader League to serverless on Google Cloud for scale at lower cost.
AWS · Google Cloud · Azure · Serverless · Terraform · CI/CD
Beyond the browser
MacCode: a native macOS app you drive from an iPhone. Distill: a terminal UI in Rust.
SwiftUI · AppKit · iOS · Rust TUI
Releases you can trust
UI covered end to end with Playwright and Cypress, gated by CI.
Playwright · Cypress · visual testing · code review
From the first conversation with design and product to the metric that moved after release.
Bundle size, load time, cost per request, benchmark scores. If it improved, you will see by how much.
I write the standards, the tooling and the docs, including a 20-chapter book on engineering with AI agents.
Computer Science · UniRitter Laureate International Universities2015–2018, academic honors in Systems Analysis. Remote from Brazil, working with US teams since 2022.