artificial-intelligence Ep1: Build Your First FREE AI Email Generator! LangChain 2025 + GPT-4o-mini (No OpenAI Credits Needed) josedacruz, November 30, 2025November 30, 2025 In this video, you’ll learn how to install LangChain 2025, set up GitHub Models for completely free LLM usage, and make your very first AI call using GPT-4o-mini. This is the perfect starting point if you want to build real-world AI applications without paying for tokens or setting up complex… Continue Reading
architecture ETag in APIs — From First Principles to Code josedacruz, October 28, 2025October 28, 2025 Ever wondered what that mysterious “ETag” header in APIs really does? 🤔 In this video, we break down ETags from the ground up — what they are, why they exist, and how they make your APIs faster and safer! You’ll see how cache validation, optimistic concurrency, and retries all rely… Continue Reading
spring-boot Spring Boot Scheduler Made Easy | @Scheduled with Fixed Rate & Cron Examples josedacruz, September 27, 2025September 27, 2025 In this video José Cruz shows you how to use the Spring Boot Scheduler to run jobs on a schedule. You’ll see when to use it, when not to, and how to externalize timings with properties. We build a simple heartbeat job that runs every 5 seconds and explain fixedRate,… Continue Reading
architecture Time-based One-Time Passwords (TOTP) Explained | Secure 2FA Made Simple josedacruz, September 26, 2025September 26, 2025 In this video, José Cruz breaks down everything you need to know about Time-based One-Time Passwords (TOTP). From the basics of what TOTP is, why it’s important for security, where it’s used, to a clear explanation of the algorithm and a live demo. Perfect for developers, IT architects, and security-conscious… Continue Reading
artificial-intelligence Understanding AI Agents & Building a Simple FAQ Chatbot in Python josedacruz, September 20, 2025September 20, 2025 In this video you’ll learn what AI agents are, why they matter, and how to build a beginner-friendly FAQ chatbot in Python using the OpenAI API.We go from basic concepts to a working demo so you can start building your own AI-powered assistants right away. What you’ll see in this… Continue Reading
architecture Locust in 20 Minutes: Install, 10-Line Test, Web UI, First Load (Beginner Friendly) josedacruz, September 10, 2025September 10, 2025 Hands-on guide to run your first load test with Locust. We go from zero to results: install Locust, write a tiny 10-line HttpUser, launch the Web UI, and start your first swarm. You’ll learn when to use Locust, how to use httpbin.org safely, how to run headless, and how to… Continue Reading
security OAuth2 & OpenID Tokens Explained | Access, ID, Refresh & Opaque Tokens josedacruz, September 1, 2025September 1, 2025 In this video, José Cruz breaks down everything you need to know about OAuth2 and OpenID Connect tokens. We’ll cover the key players in the authorization flow, explore different types of tokens (Access, ID, Refresh, Opaque), and compare JWT vs Opaque tokens. You’ll also learn real-world use cases, security best… Continue Reading
architecture Building a URL Shortener in Go | Architecture, Storage, and Real Code Walkthrough josedacruz, August 26, 2025August 26, 2025 In this video, we dive deep into building a real-world URL Shortener service in Go, from scratch. Using clean architecture principles, you’ll see how to organize your Go project using idiomatic best practices — covering everything from in-memory storage to Base62 encoding, service layering, HTTP handlers, and more! We break… Continue Reading
architecture OAuth 2.0 Resource Owner Password Credentials (ROPC) Flow – Explained in Detail josedacruz, August 20, 2025August 20, 2025 Welcome to a deep dive into one of the most controversial and risky OAuth2 flows: the Resource Owner Password Credentials (ROPC) Grant.In this visual walkthrough, we explore how it works, when (if ever) to use it, and why the industry strongly discourages its use. ⚠️ This grant type is generally… Continue Reading
spring-boot Spring Boot ApplicationRunner Explained | The Brother of CommandLineRunner josedacruz, August 19, 2025August 19, 2025 In this video, we dive deep into Spring Boot’s ApplicationRunner — the often-overlooked brother of CommandLineRunner. You’ll learn how it works, how to implement it, real-world use cases, best practices, and when not to use it. We’ll cover everything from parsing structured command-line arguments to dependency injection, ordered execution, and… Continue Reading