Development blog by Andres Parrahttps://byandrev.dev/en-ushttps://byandrev.dev/posts/optional-in-java/https://byandrev.dev/posts/optional-in-java/If you've been programming in Java for a while, you're probably very familiar with NullPointerException. It always seems to appear at the worst possible time, almost always in production, and its error message rarely tells you exactly which variable was null.Fri, 10 Jul 2026 01:53:10 GMTjavaAndres Parrahttps://byandrev.dev/posts/the-cheapest-way-to-code-with-ai/https://byandrev.dev/posts/the-cheapest-way-to-code-with-ai/OpenCode Go: GLM, Kimi, Qwen, and DeepSeek models for $5–$10/month. I analyze the limits, how to connect it, and whether it’s worth it compared to Claude.Sun, 28 Jun 2026 20:55:46 GMTaiopencodeclaudeAndres Parrahttps://byandrev.dev/posts/my-son-the-openai-server/https://byandrev.dev/posts/my-son-the-openai-server/Sam Altman has said that he finds the comparison made regarding the energy consumption of artificial intelligence unfair, and that no one questions how much energy is used to "train" a human.Mon, 01 Jun 2026 17:12:14 GMTaihumorironyAndres Parrahttps://byandrev.dev/posts/10-best-practices-for-opencode/https://byandrev.dev/posts/10-best-practices-for-opencode/OpenCode is a powerful tool, but like any tool, the difference between using it and mastering it lies in the details. These are the tips that have helped me the most in my day-to-day work.Tue, 31 Mar 2026 05:00:00 GMTaiopencodeAndres Parrahttps://byandrev.dev/posts/using-ai-for-reading-books/https://byandrev.dev/posts/using-ai-for-reading-books/Use AI to learn from books quickly, like Andrés Bilbao from Rappi. It's the ideal "entry point" for new topics before delving deeper.Wed, 25 Mar 2026 23:59:55 GMTaibooksAndres Parrahttps://byandrev.dev/posts/what-is-graphql/https://byandrev.dev/posts/what-is-graphql/GraphQL is a query language for APIs and a runtime environment for those queries, created by Facebook (Meta) in 2012 and released as open source in 2015.Wed, 18 Mar 2026 01:14:54 GMTgraphqlAndres Parrahttps://byandrev.dev/posts/how-to-use-opencode-and-github-copilot-pro-for-free-as-a-student/https://byandrev.dev/posts/how-to-use-opencode-and-github-copilot-pro-for-free-as-a-student/OpenCode is an AI-powered terminal agent that edits entire projects. It allows you to use GitHub Copilot for free for students and offers Plan and Build modes to track code changes.Fri, 13 Mar 2026 01:55:28 GMTaigithubopencodeAndres Parrahttps://byandrev.dev/posts/product-review-classification-with-naive-bayes/https://byandrev.dev/posts/product-review-classification-with-naive-bayes/A step-by-step exercise on how to classify customer reviews of products using NLP with the Naive Bayes classifier to determine if they are positive or negative.Fri, 20 Feb 2026 05:00:00 GMTainplAndres Parrahttps://byandrev.dev/posts/why-json-ld-is-important-for-seo/https://byandrev.dev/posts/why-json-ld-is-important-for-seo/Learn what JSON-LD is and how to use this linked data format to improve your website's SEO and appear in Google's knowledge panels.Sun, 15 Feb 2026 19:50:24 GMThtmlseoAndres Parrahttps://byandrev.dev/posts/linear-regression-to-predict-salary/https://byandrev.dev/posts/linear-regression-to-predict-salary/I built a linear regression model in Python with sklearn to predict salaries: cleaning, splitting, training, and metrics.Fri, 13 Feb 2026 22:49:16 GMTaimachine-learningAndres Parrahttps://byandrev.dev/posts/using-whisper-to-transcribe-videos/https://byandrev.dev/posts/using-whisper-to-transcribe-videos/Whisper is OpenAI's artificial intelligence tool that has revolutionized audio and video transcription. In this guide, you will learn how to install this open-source system on your PC or integrate it using its API to automatically generate subtitles (SRT/VTT).Fri, 13 Feb 2026 16:18:31 GMTaiopenaiAndres Parrahttps://byandrev.dev/posts/performance-metrics-in-machine-learning/https://byandrev.dev/posts/performance-metrics-in-machine-learning/Evaluating a model means measuring where it fails. In regression: MSE, RMSE, MAE, and R2. In classification: Accuracy, Precision, Recall, F1, and ROC AUC.Fri, 13 Feb 2026 00:03:45 GMTaimachine-learningAndres Parrahttps://byandrev.dev/posts/fine-turing-to-robertuito/https://byandrev.dev/posts/fine-turing-to-robertuito/Application of Fine-Tuning of a pre-trained language model, specifically designed to classify teacher evaluations into three levels of criticality.Mon, 09 Feb 2026 19:36:13 GMTaipythonAndres Parrahttps://byandrev.dev/posts/vector-and-matrix-operations/https://byandrev.dev/posts/vector-and-matrix-operations/Have you ever wondered how Netflix decides what to recommend to you or how an algorithm measures how “good” a candidate is? The answer is not magic, it's linear algebra.Thu, 05 Feb 2026 22:50:10 GMTaimachine-learningpythonAndres Parrahttps://byandrev.dev/posts/linear-algebra-basics-for-machine-learning/https://byandrev.dev/posts/linear-algebra-basics-for-machine-learning/Algebra allows us to represent and manipulate real-world problems using numbers. Thanks to algebra, we can model relationships, analyze data, and find solutions in a logical and structured way.Thu, 05 Feb 2026 20:50:24 GMTaimachine-learningpythonAndres Parrahttps://byandrev.dev/posts/using-gemma3-to-generate-teacher-feedback/https://byandrev.dev/posts/using-gemma3-to-generate-teacher-feedback/Process of integrating Gemma 3 into teacher evaluation analysis (SET). Moving from hundreds of disordered comments to structured, private summaries using local AI.Sun, 01 Feb 2026 22:17:41 GMTaiAndres Parrahttps://byandrev.dev/posts/machine-learning-fundamentals/https://byandrev.dev/posts/machine-learning-fundamentals/Machine learning is a branch of artificial intelligence that uses mathematical models to learn from data and make predictions or discover hidden patterns without being explicitly programmed.Sat, 31 Jan 2026 18:50:41 GMTaimachine-learningAndres Parrahttps://byandrev.dev/posts/ollama-in-linux/https://byandrev.dev/posts/ollama-in-linux/Ollama is a tool that makes working with Large Language Models (LLMs), like Gemma 3B, much easier. Instead of having to install a mountain of dependencies and configure complex environments, Ollama simplifies the entire process.Wed, 28 Jan 2026 05:00:00 GMTlinuxaiAndres Parrahttps://byandrev.dev/posts/customize-password-recovery-flow-with-firebase/https://byandrev.dev/posts/customize-password-recovery-flow-with-firebase/By default, when a user forgets their password, Firebase sends them to a domain such as your-project.firebaseapp.com. This can undermine user trust and aesthetics.Sun, 18 Jan 2026 23:03:58 GMTfirebaseAndres Parrahttps://byandrev.dev/posts/how-to-set-up-ssh-keys-on-github/https://byandrev.dev/posts/how-to-set-up-ssh-keys-on-github/Stop typing your username and password every time you do a git push, or if you simply want to improve security.Tue, 30 Dec 2025 02:32:47 GMTgithubgitAndres Parrahttps://byandrev.dev/posts/aws-elastic-container-service-ecs/https://byandrev.dev/posts/aws-elastic-container-service-ecs/What is Amazon ECS and how to deploy a containerized application using AWS Fargate, an Application Load Balancer (ALB), and API Gateway. Step by step on AWS.Thu, 25 Dec 2025 20:43:37 GMTawsAndres Parrahttps://byandrev.dev/posts/publishing-docker-images-to-aws-ecr/https://byandrev.dev/posts/publishing-docker-images-to-aws-ecr/Learn step by step how to build a Docker image and publish it to Amazon ECR (Elastic Container Registry). From AWS authentication to the final image push.Thu, 25 Dec 2025 19:38:45 GMTdockerawsAndres Parrahttps://byandrev.dev/posts/understanding-hexagonal-architecture/https://byandrev.dev/posts/understanding-hexagonal-architecture/Through simple examples and visual diagrams, you will discover how to decouple your business logic from frameworks and databases, improve the maintainability of your code, and write cleaner, more testable, and scalable applications.Sun, 21 Dec 2025 17:01:26 GMTAndres Parrahttps://byandrev.dev/posts/android-app-architecture-with-kotlin/https://byandrev.dev/posts/android-app-architecture-with-kotlin/The recommended architecture for Android applications with Kotlin is based on the principles of Clean Architecture, specifically adapted for mobile development. This guide will help you structure your code in a readable and maintainable way.Wed, 29 Oct 2025 02:49:20 GMTandroidkotlinAndres Parrahttps://byandrev.dev/posts/conventional-commits/https://byandrev.dev/posts/conventional-commits/Opening a project's Git history and finding messages like “various fixes,” “update,” or “fixed something” can be a nightmare. That chaos makes it impossible for anyone to understand what actually happened in the code. This is where Conventional Commits come in.Wed, 08 Oct 2025 03:06:17 GMTgitAndres Parrahttps://byandrev.dev/posts/google-stitch-ai-design-agent/https://byandrev.dev/posts/google-stitch-ai-design-agent/Creating great applications has traditionally depended on both design and development, and bridging these tasks requires significant effort. Google Labs has introduced Stitch, an artificial intelligence tool that aims to streamline this entire process.Tue, 07 Oct 2025 04:10:03 GMTaidesignAndres Parrahttps://byandrev.dev/posts/what-is-notebooklm/https://byandrev.dev/posts/what-is-notebooklm/Unlike large models such as Gemini or ChatGPT, where information is extracted from numerous web sources that may contain “hallucinations,” NotebookLM relies 100% on the sources you provide, such as PDFs, audio files, YouTube videos, Google Docs, or even articles. By working exclusively with your sources, the tolerance for hallucinations is very low.Thu, 02 Oct 2025 00:04:42 GMTaiAndres Parrahttps://byandrev.dev/posts/why-i-decided-to-leave-nextjs-and-switch-to-astro/https://byandrev.dev/posts/why-i-decided-to-leave-nextjs-and-switch-to-astro/After several attempts to adapt my personal blog to Next.js, I have finally decided to stop using it for this project. Not because it is a bad technology, far from it, but because it does not fit what I really need and want for this site. The change came after facing a series of frustrations, reading about other developers' experiences, and reevaluating my priorities.Mon, 15 Sep 2025 01:33:37 GMTastronextjsAndres Parrahttps://byandrev.dev/posts/git-workflow/https://byandrev.dev/posts/git-workflow/Git is an open-source project, originally developed in 2005 by Linus Torvalds, the famous creator of the Linux operating system kernel. It allows us to manage change logs in files, collaborative development, and know who made changes to files and when.Mon, 15 Sep 2025 01:17:34 GMTgitAndres Parrahttps://byandrev.dev/posts/learn-how-to-use-makefiles/https://byandrev.dev/posts/learn-how-to-use-makefiles/Makefiles are files located at the root of a project that allow you to automate and simplify the execution of commands in the terminal. This saves time and also improves consistency in workflows, making collaboration between team members easier and reducing errors from incomplete or mistyped commands.Tue, 09 Sep 2025 05:00:00 GMTlinuxtoolsAndres Parrahttps://byandrev.dev/posts/my-introduction-to-learning-machine-learning/https://byandrev.dev/posts/my-introduction-to-learning-machine-learning/In very simple and non-technical terms, machine learning is the science of programming computers so that they can "learn" from the data provided.Sun, 07 Sep 2025 14:28:43 GMTaimachine-learningAndres Parrahttps://byandrev.dev/posts/how-to-create-sitemap-manually-in-astro-ssr/https://byandrev.dev/posts/how-to-create-sitemap-manually-in-astro-ssr/A sitemap is a list of the pages on a website within a domain. You can usually find it on pages such as www.dominio.com/sitemap.xml. It is commonly used by web crawlers, such as search engines, to index web pages.Tue, 02 Sep 2025 05:00:00 GMTastroAndres Parrahttps://byandrev.dev/posts/build-docker-images-for-multiple-architectures/https://byandrev.dev/posts/build-docker-images-for-multiple-architectures/Applications can run on different types of processors, Intel/AMD servers (x86_64), ARM devices (Raspberry Pi, ARM servers), and Apple Silicon chips (M1/M2/M3). Building Docker images that work on all these architectures will allow you to deploy your application on any infrastructure without compatibility issues.Tue, 26 Aug 2025 18:37:33 GMTdockerAndres Parrahttps://byandrev.dev/posts/the-return-of-rpcide/https://byandrev.dev/posts/the-return-of-rpcide/Today, I finally decided to resume this project and improve it with the ideas I have in mind. It was about time.Mon, 04 Aug 2025 03:06:14 GMTrpcideAndres Parrahttps://byandrev.dev/posts/push-docker-images-to-github-container-registry/https://byandrev.dev/posts/push-docker-images-to-github-container-registry/Step-by-step guide on how to use GitHub Packages with GitHub Container Registry (ghcr.io) to publish Docker images for free.Thu, 31 Jul 2025 20:56:19 GMTdockergithubAndres Parrahttps://byandrev.dev/posts/talk-is-cheap-show-me-the-code/https://byandrev.dev/posts/talk-is-cheap-show-me-the-code/Linus Torvalds left us with a phrase that goes beyond software development: Talk is cheap. Show me the code. In this article, I share how this quote has shaped the way I work, reminding me that action beats endless planning. From side projects to large startups, true innovation comes from daring to create, even if it's imperfect.Thu, 31 Jul 2025 04:19:12 GMTAndres Parrahttps://byandrev.dev/posts/manage-installed-java-versions/https://byandrev.dev/posts/manage-installed-java-versions/One of the main drawbacks when working with Java and its ecosystem is managing multiple versions of the JDK. You may find yourself using Java 8 in one project and Java 17 in another. SDKMAN is a tool that helps us with this, allowing us to manage multiple versions of Java easily, quickly, and efficiently.Wed, 23 Jul 2025 04:21:29 GMTjavaAndres Parrahttps://byandrev.dev/posts/top-free-postgresql-hosting-services/https://byandrev.dev/posts/top-free-postgresql-hosting-services/Here is a list of the best free PostgreSQL database hosting services. These platforms offer free plans ideal for small projects, prototypes or development environments.Tue, 01 Jul 2025 21:33:05 GMTdatabasespostgresAndres Parrahttps://byandrev.dev/posts/customize-list-bullets-css/https://byandrev.dev/posts/customize-list-bullets-css/When trying to style list bullets (•) or numbers (1.) with a different color than the text, it's common to find that the style applied to the text does not affect the markers. This happens when using <ul> or <ol> tags in HTML, where applying a color directly only changes the text, but not the list markers.Wed, 25 Jun 2025 05:00:00 GMThtmlcssAndres Parrahttps://byandrev.dev/posts/finite-automaton-simulator-computation-theory-project/https://byandrev.dev/posts/finite-automaton-simulator-computation-theory-project/I built this tool with two friends for our Theory of Computation class, and I wanted to share it because I think it could be helpful for other people studying the same subject.Fri, 13 Jun 2025 05:00:00 GMTside-projectAndres Parrahttps://byandrev.dev/posts/understand-aspect-ratio-in-css/https://byandrev.dev/posts/understand-aspect-ratio-in-css/One of the fundamental elements in web interface design is the aspect ratio. In simple terms, the aspect ratio refers to the ratio between the height and width of an element, which can be images or videos.Thu, 29 Feb 2024 05:00:00 GMThtmlcssAndres Parrahttps://byandrev.dev/posts/initial-setup-for-neovim/https://byandrev.dev/posts/initial-setup-for-neovim/Neovim is a modern and renewed version of the Vim text editor. Although Neovim comes with a basic setup that works well for most users, customizing it can take your experience to the next level. In this article, we’ll explore a minimal configuration that you can implement to enhance your workflow in Neovim.Thu, 08 Feb 2024 05:00:00 GMTlinuxneovimvimAndres Parrahttps://byandrev.dev/posts/how-the-rpcide-is-built/https://byandrev.dev/posts/how-the-rpcide-is-built/Explanation of How RPCIDE is Built and How It Works, Along with Its Core Components.Sat, 26 Aug 2023 05:00:00 GMTrpcideAndres Parrahttps://byandrev.dev/posts/start-your-competitive-programming-journey/https://byandrev.dev/posts/start-your-competitive-programming-journey/Competitive programming is an exciting and challenging realm where programmers test their problem-solving skills and their ability to write efficient code within a competitive environment.Fri, 16 Jun 2023 05:00:00 GMTcompetitive-programmingAndres Parrahttps://byandrev.dev/posts/colombian-flag-with-html-and-css/https://byandrev.dev/posts/colombian-flag-with-html-and-css/HTML and CSS are often underestimated because they are not programming languages, but they are still extremely important for the web. With CSS, you can do much more than just styling, you can create drawings, illustrations, video games, and more.Sat, 19 Jun 2021 05:00:00 GMThtmlcssAndres Parra