javascript
What happens when you take an XKCD joke too literally.
CLI tool that renders package dependencies as physical tower structures. Supports PyPI, npm, and crates.io with optimal crossing minimization.
Unterminated Block Parsing.
Remend is a lightweight, standalone preprocessor that completes incomplete Markdown syntax.
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True offline-first sync for modern apps—without vendor lock-in.
🔄 A powerful, type-safe sync engine for building real-time collaborative applications. Local-first, CRDT-based, with zero-config offline support.
A tiny, zero-dependency effect system for writing pure, testable JavaScript without mocks.
Pure Effect is a tiny, zero-dependency effect system for writing pure, testable JavaScript without mocks.
It implements the "Functional Core, Imperative Shell" pattern, allowing you to decouple your business logic from external side effects like database calls or API requests. Instead of executing side effects immediately, your functions return Commands which are executed later by an interpreter.
A tiny library for building editable websites in Svelte.
Svedit (think Svelte Edit) is a tiny library for building editable websites in Svelte. You can model your content in JSON, render it with custom Svelte components, and (this is the kicker) site owners can edit their site directly in the layout — no CMS needed.
Svelte Plotting Framework.
The best visualizations are built with Svelte. A Svelte-native visualization framework based on the layered grammar of graphics principles.
Safely install NPM packages.
A security-focused npm installer that protects your projects from newly compromised packages.
The current sky at your approximate location, rendered as a CSS gradient.
New JavaScript engine written in Rust.
Brimstone is a JavaScript engine written from scratch in Rust, aiming to have full support for the JavaScript language.
Brimstone is a work in progress but already supports almost all of the JavaScript language (>97% of the ECMAScript language in test262). Not ready for use in production.
Boa is an embeddable Javascript engine written in Rust.
Boa is an experimental JavaScript lexer, parser and interpreter written in Rust 🦀, it has support for more than 90% of the latest ECMAScript specification. We continuously improve the conformance to keep up with the ever-evolving standard.
An open-source engine for P2P streaming of live and on demand video directly in a web browser HTML page.
P2P Media Loader is an open-source JavaScript library that uses modern browser technologies — like HTML5 video and WebRTC — to enable peer-to-peer (P2P) media delivery. It integrates seamlessly with popular HTML5 video players and requires no additional browser plugins or add-ons. Try the demo to see it in action.
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jQuery is a fast, small, and feature-rich JavaScript library. It makes things like HTML document traversal and manipulation, event handling, animation, and Ajax much simpler with an easy-to-use API that works across a multitude of browsers. With a combination of versatility and extensibility, jQuery has changed the way that millions of people write JavaScript.
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Visually explore, understand, and present your data.
By using easy-to-understand views, SandDance helps you find insights about your data, which in turn help you tell stories supported by data, build cases based on evidence, test hypotheses, dig deeper into surface explanations, support decisions for purchases, or relate data into a wider, real world context.
Fast, unopinionated, minimalist web framework for Node.js
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Version control for your data. Automerge is a local-first sync engine for multiplayer apps that works offline, prevents conflicts, and runs fast.
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audio waveform player JavaScript library.
Wavesurfer.js is an open-source audio visualization library for creating interactive, customizable waveforms.
Wavesurfer.js is an interactive waveform rendering and audio playback library, perfect for web applications. It leverages modern web technologies to provide a robust and visually engaging audio experience.
Prism is a lightweight, extensible syntax highlighter, built with modern web standards in mind. It’s used in millions of websites, including some of those you visit daily.
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A regular expression to match all Emoji-only symbols as per the Unicode Standard.
emoji-regex offers a regular expression to match all emoji symbols and sequences (including textual representations of emoji) as per the Unicode Standard. It’s based on emoji-test-regex-pattern, which generates (at build time) the regular expression pattern based on the Unicode Standard. As a result, emoji-regex can easily be updated whenever new emoji are added to Unicode.
The Intelligence Engine. Turn Natural Language Into Action. The Intelligence Layer for AI agents. Connect your models, tools, and data to create agentic apps that can think, act and talk to you.
An all-in-one toolkit to build agentic applications that turn natural language into real-world actions.
Want to build AI-native apps that respond to natural language? Dexto is the intelligence layer that makes it easy to build agentic apps like AI assistants and copilots. Describe your agents, plug in your tools, and watch them respond to plain English.
gpu-io is a GPU-accelerated computing library for physics simulations and other mathematical calculations.
safely install npm packages by auditing them pre-install stage. npq allows you to audit npm packages before you install them.
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Develop full-stack web apps faster.
Wasp is a compiler-driven full-stack web framework; it takes configuration and source files with your unique logic, and it generates the complete source code your the web app. Think of a Rails-like framework for React, Node.js and Prisma. Build your app in a day and deploy it with a single CLI command.
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a streaming JSON parser.
jsonriver is a simple JS library that will parse JSON incrementally as it streams in, e.g. from a network request or a language model. It gives you a sequence of increasingly complete values.
Next Generation Server Toolkit Create web servers with everything you need and deploy them wherever you prefer.
Nitro extends your Vite app with a production-ready server, designed to run anywhere. Add server routes, deploy across multiple platforms, and enjoy a zero-config experience.
A simple but powerful deobfuscator to remove common JavaScript obfuscation techniques.
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Opinionated Code Formatter.
Prettier is an opinionated code formatter. It enforces a consistent style by parsing your code and re-printing it with its own rules that take the maximum line length into account, wrapping code when necessary.
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ChatKit is a framework for building high-quality, AI-powered chat experiences. It’s designed for developers who want to add advanced conversational intelligence to their apps fast—with minimal setup and no reinventing the wheel. ChatKit delivers a complete, production-ready chat interface out of the box.
The Progressive JavaScript Framework.
🖖 Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.
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Wraps your package manager, preventing installation of malicious packages.
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One command. 25 languages. Universal multi-language runner and smart REPL written in Rust.
A universal code runner and stateful REPL written in Rust. Execute Python, JavaScript, TypeScript, Go, Rust, C, C++, Java, Kotlin, Swift, and 15 more languages with a single command.
unified is a collective of 500+ free and open source packages that work with content as structured data (ASTs). Different kinds of content can be connected together. Particularly, markdown, natural language, HTML, XML, and JavaScript are frequently used.
Content as structured data.
We compile content to syntax trees and syntax trees to content. We also provide hundreds of packages to work on the trees in between. You can build on the unified collective to make all kinds of interesting things.
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📈⚖️ Visuallize your bundle
Visualize and analyze your Rollup bundle to see which modules are taking up space.
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Fast, all‑in‑one JavaScript parser and generator for RSS, Atom, RDF, and JSON Feed, with support for popular namespaces and OPML files. Fast, all-in-one parser and generator for RSS, Atom, RDF, and JSON Feed, with support for Podcast, iTunes, Dublin Core, and OPML files.
Feedsmith offers universal and format‑specific parsers that maintain the original feed structure in a clean, object-oriented format while intelligently normalizing legacy elements. Access all feed data without compromising simplicity.
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Comprehensive detection tool for NPM supply chain attacks, specifically designed to identify and prevent the Shai-Hulud worm that compromised 500+ packages including CrowdStrike npm packages in 2025.
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A simple, barebones "multiplayer" middleware for zustand.
A barebones middleware to sync zustand stores across multiple clients. zustand-sync uses JSON Patch (RFC 6902) under the hood to translate state changes into patches that can be sent over a transport layer.
Knockout makes it easier to create rich, responsive UIs with JavaScript.
Knockout is a JavaScript MVVM (a modern variant of MVC) library that makes it easier to create rich, desktop-like user interfaces with JavaScript and HTML. It uses observers to make your UI automatically stay in sync with an underlying data model, along with a powerful and extensible set of declarative bindings to enable productive development.
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How to stay safe from NPM supply chain attacks.
The NPM ecosystem is no stranger to compromises, supply-chain attacks, malware, spam, phishing, incidents, or even trolls. In this repository, I have consolidated a list of information you might find useful in securing yourself against these incidents.
JavaScript/TypeScript-native, low-boilerplate, object-capability RPC system.
Cap'n Web is more expressive than almost every other RPC system, because it implements an object-capability RPC model.
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JavaScript API for Chrome and Firefox.
Puppeteer is a JavaScript library which provides a high-level API to control Chrome or Firefox over the DevTools Protocol or WebDriver BiDi. Puppeteer runs in the headless (no visible UI) by default.
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📝 Algorithms and data structures implemented in JavaScript with explanations and links to further readings.
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Extensible Code Editor
CodeMirror is a code editor component for the web. It can be used in websites to implement a text input field with support for many editing features, and has a rich programming interface to allow further extension.
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Components for React, Svelte and Vue.
Integrate fully functional UI widgets for data management, project planning, or file organization in minutes. Get started with the framework of your choice: React, Svelte or Vue.
TypeScript library for regex equivalence, intersection, complement and other utilities that go beyond string matching.
Zero-dependency TypeScript library for regex utilities that go beyond string matching. These are surprisingly hard to come by for any programming language. ✨
The easiest way to build interactive medical imaging web applications. Supported by the Open Health Imaging Foundation.
Cornerstone is a set of JavaScript libraries that can be used to build web-based medical imaging applications. It provides a framework to build radiology applications such as the OHIF Viewer.
An open-source framework for building AI-powered apps, built and used in production by Google
Open-source framework for building AI-powered apps in JavaScript, Go, and Python, built and used in production by Google
It offers a unified interface for integrating AI models from providers like Google, OpenAI, Anthropic, Ollama, and more. Rapidly build and deploy production-ready chatbots, automations, and recommendation systems using streamlined APIs for multimodal content, structured outputs, tool calling, and agentic workflows.
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Ecosystem Performance. Cleanup, Speedup, Levelup. One package at a time.
The e18e project is an initiative to bring together the groups and individuals who are passionate about improving performance of the JavaScript ecosystem.
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Safe deep property access in 120 bytes. x = dlv(obj, 'a.b.x').
Safely get a dot-notated path within a nested object, with ability to return a default if the full key path does not exist or the value is undefined
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Simple and performant reactivity for building user interfaces. A declarative, efficient, and flexible JavaScript library for building user interfaces.
Solid is a declarative JavaScript library for creating user interfaces. Instead of using a Virtual DOM, it compiles its templates to real DOM nodes and updates them with fine-grained reactions. Declare your state and use it throughout your app, and when a piece of state changes, only the code that depends on it will rerun.
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Beautiful and accessible math in all browsers
A JavaScript display engine for mathematics that works in all browsers. No more setup for readers. It just works.
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Relocate resource intensive third-party scripts off of the main thread and into a web worker. 🎉
Partytown is a lazy-loaded library to help relocate resource-intensive scripts into a web worker, and off of the main thread. Its goal is to help speed up sites by dedicating the main thread to your code, and offloading third-party scripts to a web worker.
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What's the best JavaScript minifier?
🏃♂️🏃♀️🏃 JS minification benchmarks: babel-minify, esbuild, terser, uglify-js, swc, google closure compiler, tdewolff/minify, oxc-minify
AI-assisted SAST, SCA and Secrets Detection. Lightweight static analysis for many languages. Find bug variants with patterns that look like source code.
Semgrep is a fast, open-source, static analysis tool that searches code, finds bugs, and enforces secure guardrails and coding standards. Semgrep supports 30+ languages and can run in an IDE, as a pre-commit check, and as part of CI/CD workflows.
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Context-aware web performance for everyone.
Obs.js uses the Navigator and Battery APIs to get contextual information about your users’ connection strength and battery status. You can use this data to adapt your site/app to their environment, or beacon the data off to an analytics endpoint.
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Rush makes life easier for JavaScript developers who build and publish many packages from a common Git repo. If you're looking to break up your giant application into smaller pieces, and you already realized why it doesn't work to put each package in a separate repo... then Rush is for you!
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The huggingface_hub library allows you to interact with the Hugging Face Hub, a machine learning platform for creators and collaborators. Discover pre-trained models and datasets for your projects or play with the hundreds of machine learning apps hosted on the Hub. You can also create and share your own models and datasets with the community. The huggingface_hub library provides a simple way to do all these things with Python.
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In this short article, I will walk you through how I implemented it in Typescript (JS), how you can adopt MCP too and how it's going to make Agentic AI way simpler going forward.
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This open-source curriculum introduces the fundamentals of Model Context Protocol (MCP) through real-world, cross-language examples in .NET, Java, TypeScript, JavaScript, Rust and Python. Designed for developers, it focuses on practical techniques for building modular, scalable, and secure AI workflows from session setup to service orchestration.