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I'm Samuel Fajreldines I am a specialist in the entire JavaScript and TypeScript ecosystem (including Node.js, React, Angular and Vue.js) I am expert in AI and in creating AI integrated solutions I am expert in DevOps and Serverless Architecture (AWS, Google Cloud and Azure) I am expert in PHP and its frameworks (such as Codeigniter and Laravel). |
Samuel FajreldinesI am a specialist in the entire JavaScript and TypeScript ecosystem. I am expert in AI and in creating AI integrated solutions. I am expert in DevOps and Serverless Architecture I am expert in PHP and its frameworks.
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In-depth guides, tutorials and real-world engineering write-ups by Samuel Fajreldines on JavaScript & TypeScript, Node.js, Artificial Intelligence, DevOps, Serverless, testing and software architecture.
By Samuel Fajreldines · · Backend Development
Learn how to serve TypeScript type definitions for Elysia's Eden Treaty client in both development and production environments. This guide covers static file serving in Cloud Run, on-the-fly generation during development...
By Samuel Fajreldines · · Artificial Intelligence
**Claudiomiro** is an AI-powered CLI tool that automates the complete software development lifecycle. Unlike simple code generators, Claudiomiro thinks through complex problems, analyzes codebases, identifies patterns, a...
By Samuel Fajreldines · · Artificial Intelligence
A **Knowledge Graph** is a sophisticated data structure that stores information as interconnected entities and relationships, enabling AI systems to understand context, patterns, and connections across different types of...
By Samuel Fajreldines · · Frontend Development
Learn how to implement i18n in React and on the backend to deliver a seamless experience for global audiences, focusing on best practices, code examples, and scaling strategies.
By Samuel Fajreldines · · Artificial Intelligence
Deep dive into implementing a production-ready AI fitness agent using LangChain.js with structured tools, proper prompting, and intelligent context retrieval.
SecurityScoreCard
Nov. 2023 - Present
New York, United States
Senior Software Engineer
I joined SecurityScorecard, a leading organization with over 400 employees, as a Senior Software Engineer, focusing primarily on frontend development. My role involves designing and building user-centric interfaces, optimizing performance, and ensuring seamless user experiences across our web applications.
I specialize in modern frontend technologies, crafting scalable and maintainable codebases while integrating them efficiently with backend systems. I also contribute to UI/UX improvements, enhancing usability and accessibility to align with industry best practices.
Beyond development, I collaborate closely with designers, product managers, and backend engineers to ensure cohesive and intuitive applications. By leveraging my expertise in frontend architecture and performance optimization, I help SecurityScorecard deliver high-quality cybersecurity insights through fast, responsive, and visually compelling interfaces.
Highlights:
Reduced system bundle size by 90%, leading to an 8x improvement in load speed.
Eliminated system duplicate requests, improving backend efficiency and reducing server load.
Technologies Used:
Node.js Terraform React Redux / React Query Typescript AWS Playwright CypressMahisoft Inc
Dec. 2022 - Nov. 2023
New York, United States
Senior Software Engineer
I joined Mahisoft as a Senior Software Engineer, where I serve as the lead technologist responsible for all the technology and systems related to the projects under my charge.
I specialize in translating the directives from the board members of Top Trader League into functional, scalable code. My work often involves architecting backend systems, optimizing database queries, and building responsive, user-friendly front-end interfaces to convert the leadership team's vision into tangible results that drive business impact.
One of my key responsibilities is writing efficient and maintainable code that not only meets but exceeds the technical requirements, ensuring that our software solutions are robust and scalable.
Highlights:
Implemented an asynchronous messaging system, reducing database overuse and improving efficiency.
Implemented serverless architecture using Google Cloud, enabling a highly scalable and cost-efficient infrastructure.
Technologies Used:
Node.js PHP (Laravel) React Redux / React Query Google Cloud AWS TerraformVagalume Midia
Aug. 2021 - Dec. 2022
Senior Software Engineer
I was privileged to join Vagalume as a Senior Full Stack Developer, brought on board by the company's owner, Daniel. At Vagalume, I was the go-to person for a wide array of tasks spanning both coding and DevOps.
As the largest enterprise I've worked for in terms of user base and visitor traffic, Vagalume provided a complex and stimulating environment where I honed my skills in DevOps and high-scalability systems. The guidance and mentorship from Daniel have been invaluable, shaping not only my professional development but also forging a lasting friendship.
One of my most notable contributions was the complete overhaul of Vagalume's radio systems. This involved rearchitecting the infrastructure and rewriting the codebase. The end result was a significant boost in system performance and a marked reduction in AWS operating costs.
Highlights:
Learned DevOps under Daniel, one of the world's top AWS experts, gaining deep expertise in cloud infrastructure.
Refactored Vagalume Radios in Node.js from scratch, enhancing efficiency, scalability, and reducing costs.
Technologies Used:
Node.js PHP React Redux / React Query Vue.js AWS TerraformAnilha
Feb. 2019 - Dec. 2021
Side period
Founder
I believe that the best way to learn is by doing something with what you are learning.
So, during my free time, I started an app called Anilha. Anilha means dumbbell in Portuguese and the app was designed to help users with flexible diet and workouts.
I can say with 100% certainty that Anilha was the biggest factor in my learning process.
Technologies Used:
Node.js Ionic Angular AWS Lambda DynamoDB TerraformSecretária Virtual
Sep. 2019 - Aug. 2021
Senior Software Engineer
I had the privilege of being recruited by Leonardo Leffa, a close friend and mentor, to oversee the technology initiatives across a diverse portfolio of enterprises under the umbrella of Secretaria Virtual. In this capacity, my responsibilities extended beyond mere code writing to shaping the development processes and workflows that governed how tasks were requested by users and collaborators within the company.
During my tenure at Secretaria Virtual, I led an array of complex development projects as directed by the company's senior leadership. My scope of work covered:
Infrastructure Development: Ensuring robust, scalable backend solutions.
System Development: Architecting and coding business-critical applications.
Monitoring & Testing: Establishing metrics and frameworks to ensure software reliability.
I was instrumental in ushering the company into a new technological era by advocating for and implementing cloud computing solutions and continuous integration practices. Moreover, I led the shift towards Agile development by introducing the Scrum methodology, fostering a more collaborative and efficient work environment.
Technologies Used:
Node.js PHP AngularJS Laravel CodeIgniter IonicE-TRUST
Sep. 2017 - Sep. 2019
Senior Software Engineer
Operating in the critical sphere of Information Security, E-trust necessitates the utmost safeguarding of data across all its platforms.
As a Senior Developer at E-trust, I was entrusted with a multi-faceted role that included not only coding but also shaping the development processes in collaboration with upper management. My primary mission was to innovate new features while modernizing both frontend and backend architectures of our Horacius system—all while maintaining rigorous security protocols.
In pursuit of code excellence and efficient workflows, I established clean coding practices based on Object-Oriented Programming (OOP) principles. I was also instrumental in introducing continuous integration processes, which included automated migrations and code validation through specialized robotic checks.
Among my proudest achievements was the complete revamping of the Horacius system's frontend. The challenge was not just to modernize it but also to ensure backward compatibility with legacy systems. The successful implementation resonated well with our client base, which includes some of Brazil's largest banks and corporations.
Being at the forefront of creating the company's code culture, I was exposed to substantial responsibilities and unparalleled learning experiences, particularly in the realms of security and DevOps.
Technologies Used:
PHP Microsoft SQL Server Windows ServerUniRitter
2015 - 2018
UniRitter Laureate International Universities
Bachelor of Computer Science
Engaged in a rigorous program at UniRitter Laureate International Universities, renowned as one of the top institutions in the country. Excelled in System Analysis and Development, receiving accolades for academic excellence. Although I did not complete the degree due to career opportunities in the field, my foundational education and achievements at UniRitter have significantly contributed to my professional capabilities and expertise.
Long-Term Memory for AI: How Graphiti Works for Building Real Smart Applications
Graphiti transforms ever-changing data into a bi-temporal knowledge graph that your AI agents can query in milliseconds. In this guide you'll learn why it exists, how it works, and how to build a Personal Financial AI Coach that learns from your daily spending habits and provides personalized advice to help you make better money decisions. 1 What is Graphiti? Graphiti is an open-source Python framework for building real-time, bi-temporal knowledge graphs tailored to retri...
https://www.samuelfaj.com/posts/2025-07-14-222718/index.html
Mastering Multi-Cloud with Terraform: Deploying Infrastructure on Google Cloud and AWS
The proliferation of cloud platforms has ushered in a new era of flexibility and opportunity for software professionals and organizations. While choosing a single provider can streamline certain operations, leveraging multiple clouds has become increasingly attractive for achieving redundancy, optimizing costs, and accessing the unique offerings of each provider. This is where Infrastructure as Code (IaC) tools like Terraform come into play. By using Terraform to deploy to bo...
https://www.samuelfaj.com/posts/2025-01-24-115800/index.html
Mastering Transactions in Modern Software Engineering
Transactions lie at the heart of any robust application that deals with sensitive or critical data updates. Whether you're developing a high-traffic e-commerce platform, a financial services dashboard, or a social media application, the integrity of your data hinges on well-established transaction mechanisms. In modern Software Engineering, the term "transactions" extends beyond simple database commits and rollbacks. It includes distributed transactions, sophisticated concurr...
https://www.samuelfaj.com/posts/2025-02-11-141552/index.html
The Ultimate Guide to Using React Query: Why and How to Implement It
Introduction In the modern web development landscape, efficient data fetching and state management are crucial for building responsive and user-friendly applications. React Query, often described as "the missing data-fetching library for React," simplifies these aspects by providing powerful hooks for fetching, caching, and updating asynchronous data in React applications. In this comprehensive guide, we'll explore why React Query has become an indispensable tool fo...
https://www.samuelfaj.com/posts/2024-10-22-182435/index.html
Implementing Event-Driven Architecture with AWS and Node.js
Modern applications demand scalability, flexibility, and real-time responsiveness. To meet these requirements, developers are increasingly turning to event-driven architecture (EDA), a paradigm that decouples components and enables systems to react to events as they occur. In this post, we'll explore how to implement an event-driven architecture using AWS and Node.js, unlocking the full potential of cloud-native applications. Understanding Event-Driven Architecture At its cor...
https://www.samuelfaj.com/posts/2025-01-20-163757/index.html
All the Types of Tests in Software Development
Software testing is essential for delivering reliable, scalable, and secure applications. By rigorously testing every part of an application, teams catch bugs earlier, reduce technical debt, and achieve higher quality standards. Below is a detailed overview of the most common types of tests in software development, along with practical examples using JavaScript and Node.js. This guide demonstrates how multiple levels of testing can be integrated into a comprehensive testing s...
https://www.samuelfaj.com/posts/2025-02-25-010444/index.html
