10 Open Source Gems To Become The Ultimate Developer 🔥
TL;DR
Every day we use different technological tools, already on automatism, although we have not heard about them before.
With the knowledge of the new, we gain that competitiveness in the market that will provide us with what we want, be it an online store or a simple calculator.
In this article, I have collected some tools, knowledge of which will help you become the ultimate developer.
Let's get started! 🏎️
1. 🐜 HMPL.js - Server-oriented customizable templating for JavaScript
Let's start with a small template language that allows you to get components from the server and display them on the client. Due to its syntax, applications are quite small.
It’s integrated with JSON5 and DOMPurify, and keeps your JS bundles small. If you care about performance and like having full control, this one's worth a look.
2. 🐈⬛ Nest.js - A progressive Node.js framework for building efficient, scalable, and enterprise-grade server-side applications
If you’ve ever wished Express had a bit more structure, Nest.js is the upgrade you’ve been looking for. It brings TypeScript, OOP, and a modular architecture to Node.js development.
Nest is a framework for building efficient, scalable Node.js server-side applications. It uses modern JavaScript, is built with TypeScript (preserves compatibility with pure JavaScript) and combines elements of OOP (Object Oriented Programming), FP (Functional Programming), and FRP (Functional Reactive Programming).
3. 🧠 Agent TARS - The Open-sourced Multimodal AI Agent Stack connecting Cutting-edge AI Models and Agent Infra.
None of my lists are complete without AI projects and this time will be no exception. Especially when it comes to ByteDance and its new product. With this tool, you can implement a convenient UI for AI agents either in a browser or in a terminal.
agent-tars --provider openai --model gpt-4o --apiKey {apiKey}
Agent TARS is a general multimodal AI Agent stack, it brings the power of GUI Agent and Vision into your terminal, computer, browser and product.
4. 🐇 Bun - Incredibly fast JavaScript runtime, bundler, test runner, and package manager – all in one
If you think that Node.js is slow today, then yes, you are right. I once said about Deno that it is one of the fastest environments, but probably Bun is the fastest today or was at least a couple of years ago.
Bun is an all-in-one toolkit for JavaScript and TypeScript apps. It ships as a single executable called bun.
5. 🕷 Supertest - Super-agent driven library for testing node.js HTTP servers using a fluent API
Yes, a bit old, of course, but no less relevant module for testing http. Usually, other, more recent solutions are used, but this module is also valid even in 2025. Example of use:
const request = require('supertest');
request(app)
.get('/user')
.expect('Content-Type', /json/);
The motivation with this module is to provide a high-level abstraction for testing HTTP, while still allowing you to drop down to the lower-level API provided by superagent.
6. 👀 Mockoon - Easiest and quickest way to run mock APIs locally
A fairly new project for local API mocking during development. Notable for its interface, as well as integration capabilities.
Mockoon is the easiest and quickest way to design and run mock APIs. No remote deployment, no account required, free and open-source.
💎 Check out Mockoon repository
7. 💼 Frappe HR - Open Source HR and Payroll Software
The next project is an open source business solution for HR management from Frappe. This company has been around for a long time and has a really big name in the industry, as you may have used (or are using) its ERPNext product if you work as a manager.
Frappe HR has everything you need to drive excellence within the company. It's a complete HRMS solution with over 13 different modules right from Employee Management, Onboarding, Leaves, to Payroll, Taxation, and more!
8. 🖋️ Appwrite - Build like a team of hundreds_
This is a very useful ultimate platform for developers, which has many functions related to databases, connections between other developers and much more. This platform is used by such giants as Tik Tok, Nestle, Apple and others. But even one developer can handle it and make a quality product.
Appwrite is a backend platform for developing Web, Mobile, and Flutter applications. Built with the open source community and optimized for developer experience in the coding languages you love.
9. 🔗 LangChain - Build context-aware reasoning applications
Today, it is impossible to imagine development without artificial intelligence, and one of the first projects in this direction is LangChain. This is probably one of the fastest growing projects on GitHub, as the industry was simply blown away by the release of ChatGPT and this project combined the concepts of framework and AI prompt_template.invoke().
LangChain is a framework for building LLM-powered applications. It helps you chain together interoperable components and third-party integrations to simplify AI application development — all while future-proofing decisions as the underlying technology evolves.
✅ Conclusion
Knowing all these tools and using them at the right time, you can pump yourself up and become a real ultimate developer! And, regardless of what language you program in.
Thank you very much for reading this article ❤️!
What other open source tools do you use? It would be interesting to know!
P.S. Also, don't forget to help me and star HMPL!