The article highlights 12 open source tools that every developer should know about to enhance their skills and competitiveness in the market.HMPL is a server-oriented templating language for JavaScript that allows for small applications with the same UI as modern frameworks.Docker Compose, a tool for running multi-container applications on Docker, is essential for modern development.LangChain is a framework for building context-aware reasoning applications using LLM-powered applications.Ollama offers a collection of popular AI models for developers to utilize in their projects.Vue-Vapor, a variant of Vue, provides rendering without using Virtual DOM and offers fast speeds among frameworks.Shadcn UI is a popular component library for building modern design applications with accessible and customizable components.Postiz is an ultimate social media scheduling tool with AI features for managing social media presence effectively.Bun is an incredibly fast JavaScript runtime, bundler, test runner, and package manager for JavaScript and TypeScript apps.Nest.js is a progressive Node.js framework suited for building efficient, scalable server-side applications with TypeScript.VuePress is a minimalistic Vue-powered static site generator useful for generating static sites from Markdown content.