Open-source alternatives to Brython

python-for-android is a toolchain that compiles Python applications and their dependencies into installable Android APK or AAB packages. It bundles a Python interpreter and standard library into an Android package, enabling Python code to run natively on mobile devices. The project provides a recipe-based build engine that automates dependency resolution, version pinning, and custom compilation steps for Android targets. The system cross-compiles Python and native C-extension libraries for multiple Android CPU architectures, producing separate native binaries for each target and packaging the

ReScript is a statically typed programming language and compiler designed to transform type-safe source code into efficient, human-readable JavaScript. It functions as a transpiler that enforces data consistency and prevents runtime errors through static type analysis for both web and server applications. The project distinguishes itself as an incremental build system that analyzes dependency graphs to recompile only modified files and their dependents. It includes a JSX compatible compiler for building user interfaces and provides a framework for bridging type-safe code with existing JavaScr

This is a collection of small JavaScript projects and code samples that demonstrate the implementation of fundamental programming concepts through practical applications. The repository serves as a reference for building interactive user interfaces, managing application state, and integrating external APIs using vanilla JavaScript. The project focuses on the use of standard JavaScript without external frameworks to create interface elements such as modals, sliders, and galleries. It provides examples of organizing complex application logic through object-oriented patterns using classes and ob

TeaVM is a Java bytecode transpiler and browser-based JVM runtime that converts compiled Java class files into JavaScript or WebAssembly. It functions as a compiler and build pipeline tool that enables applications written in various JVM languages to execute natively within a web browser. The project distinguishes itself by transforming bytecode directly into optimized web formats without requiring the original source code. It includes a WebAssembly bytecode compiler for high-performance execution and a specialized emulation system to handle asynchronous multithreading within the single-threa

Scala.js is a compiler and cross-platform language toolchain that transforms Scala source code into JavaScript or WebAssembly. It functions as a statically typed tool for the JavaScript ecosystem, enabling the development of applications for web browsers and Node.js environments. The project serves as a JavaScript interop framework, allowing the creation of type-safe facades and bindings to interact with external libraries and global objects. It provides mechanisms for both static and dynamic JavaScript invocation, including the generation of TypeScript bindings and the ability to export inte

Reason is a strongly typed functional language and multi-target compiler designed to produce either JavaScript for web environments or native machine code for operating systems. It serves as an OCaml-compatible language that shares an abstract syntax tree with OCaml, providing a practical syntax for the OCaml ecosystem. The project functions as a type-safe frontend language, incorporating JSX support to build user interfaces through structural elements that translate into type-safe function calls. It enables deep integration with the JavaScript ecosystem, allowing the use of existing librarie

This repository contains the HTML specification, which defines the core standards for web page structuring, content organization, and document rendering. It establishes the fundamental algorithms for state-machine-based tokenization, tree construction for the document object model, and origin-based security isolation. The specification provides a framework for defining custom elements with independent lifecycles and registries. It also details the requirements for cross-document communication, session history management, and the synchronization of interface properties with content attributes.

Cash is a lightweight DOM manipulation library and HTML element wrapper designed as an alternative to jQuery for selecting and modifying elements in modern browsers. It functions as a modular DOM framework and JavaScript utility library, providing a system to wrap DOM nodes into actionable collections for batch processing. The project is built with a modular design that supports tree-shaking, allowing build tools to exclude unused methods to minimize the final bundle size. It provides mechanisms for extending the core functionality and collection prototypes to implement reusable plugins and c

Eel is a framework for creating desktop applications using a Python backend and a web-based frontend. It acts as a bidirectional bridge between Python and JavaScript, allowing developers to build graphical user interfaces with HTML and JavaScript that communicate with local system logic. The project facilitates two-way communication by enabling the exposure of Python functions to the browser and allowing the backend to trigger JavaScript functions. It uses a local server to render web interfaces as standalone desktop windows and provides tools to bundle the Python code and web assets into a s

This project is a functional programming compiler and JavaScript transpiler that transforms a statically typed language into optimized JavaScript for web browsers. It serves as a frontend architecture framework, providing a static type system and a package manager that enforces semantic versioning. The compiler uses a type-checking engine with automatic type inference to prevent runtime errors and guide code refactoring. It implements a structural pattern for managing application state and rendering user interfaces through a virtual DOM, utilizing immutable data and purity-based state transit

Cash is a lightweight JavaScript library for selecting and modifying HTML elements in modern browsers. It functions as a chainable element wrapper and DOM manipulation utility, providing a minimal alternative for managing browser DOM operations. The library uses a collection-based wrapper for DOM nodes, allowing multiple modifications and style updates to be performed in a single sequence. It is designed to provide a similar API for event handling and element management while maintaining a small footprint. The project covers a wide range of DOM manipulation capabilities, including element se

Reason is a statically typed programming language and compiler based on the OCaml ecosystem. It translates high-level, type-safe source code into either JavaScript or OCaml output, providing a typed alternative for web and system development. The language focuses on providing rigorous type safety and a robust module system while integrating with the JavaScript ecosystem. It allows for the development of applications that leverage existing JavaScript libraries while utilizing a more rigid type system to eliminate common runtime crashes and data mismatches. The project covers capabilities incl

miniblink49 is a stripped-down Blink browser kernel and embedded web UI framework used to integrate HTML user interfaces into native C++ applications. It functions as a C++ JavaScript interop bridge that maps high-level script calls to low-level native logic and provides a resource-optimized headless browser engine for processing web content without a graphical interface. The project enables custom browser environment control by bypassing cross-origin security policies to allow requests across different domains. It further allows for the interception of network resources to replace remote ass

This project is a vanilla JavaScript reference guide and implementation collection designed to replace legacy libraries with native browser patterns. It provides a set of native JavaScript patterns for selecting, modifying, and navigating HTML elements, alongside a web API implementation guide for handling events and styles. The project serves as a reference for implementing asynchronous JavaScript patterns using native promises and fetch for remote data and background tasks. It also includes a client-side utility collection for performing data transformations, type validation, and element me

Binaryen is a WebAssembly compiler toolchain and optimizer designed to transform, validate, and shrink binary modules. It provides a comprehensive intermediate representation framework that converts binary code into a single-assignment form to enable advanced program analysis and code transformation. The project includes a specialized transformation engine that applies iterative optimization passes to increase execution speed and reduce binary size. Additionally, it functions as a transpiler that translates WebAssembly binary modules into executable JavaScript for environments that lack nativ

Opal is a Ruby frontend framework and compiler that translates Ruby source code into JavaScript. It functions as a web runtime that allows for the development of client-side web applications using Ruby instead of JavaScript. The project includes a Ruby HTML template engine that evaluates Ruby code embedded directly within markup files. It further integrates with JavaScript environments by bundling core libraries and dependencies into a distribution string for execution in a web browser. The system provides capabilities for Ruby to JavaScript compilation and the ability to encode and decode B

This project provides a full Python interpreter compiled to WebAssembly, enabling the execution of Python code and scientific libraries directly within web browsers and server-side environments. By bridging the gap between language runtimes, it allows developers to run computational tasks, manage packages, and perform data analysis in client-side environments without requiring a backend server. The platform distinguishes itself through a comprehensive foreign function interface that enables bidirectional data exchange, object proxying, and function calling between Python and JavaScript. It in

Dragula is a JavaScript drag and drop library and DOM element manipulator used to move and reorder HTML elements between multiple containers. It functions as a UI interaction framework and event manager that tracks drag lifecycles to facilitate the movement of elements within a web browser interface. The library distinguishes itself through configurable constraint validation, allowing developers to define which elements are draggable and which containers are permitted drop targets. It supports specialized interaction patterns such as element cloning, the use of specific drag handles to restri

CoffeeScript is a source-to-source transpiler that transforms a concise high-level syntax into standard JavaScript. It enables the development of logic for web applications and server-side environments by converting source code into a format compatible with browsers and server runtimes. The project provides a workflow for rapid prototyping and script execution automation, allowing users to run source files through a compiler and execute the resulting code immediately without a manual build step. The tooling leverages lexical analysis and abstract syntax tree transformations to manipulate cod

Sprint is a lightweight DOM manipulation and event handling library. It provides a minimal set of utilities for selecting, modifying, and traversing elements within the browser document object model. The library utilizes a selector engine to isolate specific document nodes using CSS-like patterns and positional indices. It encapsulates raw DOM elements within a wrapper object to provide a consistent API for updating element attributes, styles, and content. The toolset covers browser event management for attaching and detaching interaction handlers, as well as document tree navigation to loca

Hermes is a mobile-optimized JavaScript runtime and engine designed for React Native. It functions as an ahead-of-time bytecode compiler that converts JavaScript source code into a dense binary format during the build process to eliminate the need for parsing and compilation at runtime. The engine features a baseline JIT compiler that generates native machine code for frequently called functions to improve performance after the initial launch. It also includes a mobile-optimized garbage collector that precisely identifies reachable objects to minimize memory overhead and pause times on resour

This is the Chinese translation of The Modern JavaScript Tutorial, an open-source, community-driven project that teaches JavaScript from fundamentals to advanced topics based on the latest ECMAScript specification. The project covers the full JavaScript language, including object-oriented programming, and provides comprehensive instruction on browser programming, DOM manipulation, and client-side web development. The tutorial is structured as a multi-language translation framework, with each chapter and article organized into numbered folders for clear navigation. Contributors can translate M

Instantclick is a client-side navigation enhancer and JavaScript page preloader. It intercepts HTTP requests to update page titles and content via asynchronous requests, avoiding full browser refreshes to eliminate white flashes during navigation. The project reduces perceived frontend latency by fetching linked content in the background when a user hovers over a hyperlink. This intent-based preloading ensures content is ready by the time a user clicks. The tool manages the browsing experience through client-side history manipulation and DOM-based content injection. It also includes a custom

This project is a Lisp interpreter implementation guide and framework designed to teach the core principles of programming language design. It provides a structured, step-by-step technical framework for building a functional Lisp language from scratch, featuring a specialized interpreter engine and an S-expression parser that converts syntax into abstract syntax trees. The project emphasizes a code-as-data metaprogramming framework, enabling the implementation of macros, quoting, and quasiquoting to transform expressions during evaluation. It is designed with host language agnosticism, allowi

This is a responsive navigation JavaScript library used to create mobile-friendly menus with screen size detection and touch support. It functions as an accessible navigation menu and a client-side layout switcher that transitions between mobile and desktop views without external dependencies. The project serves as a menu animation tool that enables smooth CSS transitions and height-based animations when toggling navigation overlays. It utilizes native browser APIs to manage interface states and ensure the navigation remains functional for screen readers and users without JavaScript. The lib

Moveable! Draggable! Resizable! Scalable! Rotatable! Warpable! Pinchable! Groupable! Snappable!

htmlparser2 is a collection of tools for high-performance markup parsing, DOM manipulation, and incremental stream processing. It functions as an HTML and XML parser that converts markup strings into structured object trees, alongside a streaming markup parser designed for memory-efficient processing of large documents. The project includes a DOM manipulation library for querying, modifying, and serializing document object model trees. It also provides a web feed parser to extract structured metadata and entries from RSS, RDF, and Atom feeds. The library covers broad capabilities in data par