Open-source alternatives to Webextensions Examples

Scriptcat is a user script manager and browser extension designed to install, execute, and manage custom JavaScript scripts to modify website behavior and extend browser functionality. It features a JavaScript sandbox environment that provides specialized APIs for storage, cookies, and system notifications, alongside a cloud-synced script repository to keep subscriptions and configurations consistent across multiple devices. The project includes an in-browser script editor for writing, testing, and debugging code directly within the browser. It also incorporates a cross-domain request engine

Firefox is a cross-platform web browser engine designed to render web content, execute JavaScript, and manage secure browsing sessions. It utilizes a multi-process isolation architecture that distributes browser tasks across independent operating system processes to ensure stability and prevent site-specific failures from impacting the entire application. The engine incorporates a sandboxed execution environment to restrict web content and untrusted scripts to isolated memory compartments, enforcing security policies that prevent unauthorized access to system resources. The project distinguis

Tampermonkey is a userscript manager used for browser behavior modification and web page automation. It allows for the installation and management of custom scripts that inject JavaScript into web pages to change their appearance or functionality. The project enables cross-browser script synchronization to maintain a consistent set of modifications across multiple devices. It provides a mechanism to manage custom userscript collections and synchronize them via cloud accounts. The system covers a broad range of capabilities including the automation of repetitive tasks on specific websites and

This repository serves as a comprehensive reference library for browser extension development, providing a collection of code samples and implementation patterns. It is designed to help developers understand the requirements for building extensions that adhere to current manifest standards, specifically focusing on the transition to and implementation of version three specifications. The project provides functional examples for core extension capabilities, including the use of event-driven background service workers, isolated content script injection, and message-passing for inter-process com

pydoll is a Chrome DevTools Protocol automation library and headless browser controller used for web data extraction and parallel browser automation. It controls Chromium-based browsers via direct WebSocket connections, allowing it to manage isolated browser contexts and tabs while bypassing the overhead and detection associated with WebDriver. The project features an anti-bot evasion framework that mimics natural human behavior, including mouse movements generated via Bezier curves and variable typing patterns. It provides specialized stealth capabilities to bypass behavioral analysis and au

N-Tab is a browser extension designed to manage browser tab lifecycles by consolidating open web pages into organized, virtual sessions. It functions as a session management tool that allows users to group tabs into custom folders, recover recently closed pages, and reduce system memory usage by offloading active tabs into a centralized interface. The extension distinguishes itself through its support for cross-device synchronization, enabling users to back up and share saved tab configurations across multiple browser instances via remote cloud storage. It also provides a declarative command

Notion Enhancer is a customization framework and desktop application modifier designed to inject JavaScript and CSS into Notion. It functions as a plugin system and theme engine that modifies the interface and core application behavior. The project enables the overriding of internal software logic and the injection of custom scripts to change default behaviors. It includes a theme engine for overriding CSS variables to apply custom visual schemes and provides support for right-to-left text direction. The framework covers a range of capabilities including workflow automation through user inpu

AdguardFilters is a collection of curated adblock filter lists, content blocking rulesets, and DNS blocklists. Its primary purpose is to provide the rules necessary to identify and remove advertisements, tracking scripts, and intrusive elements across web browsers and applications. The project includes specialized rules for cosmetic filtering to hide layout gaps and a malware domain database to block phishing and spyware destinations. It provides distinct filtering sets for different regions and purposes, such as social media blocking. The repository covers broad capability areas including m

openapi-devtools is a browser extension and OpenAPI specification generator that captures network traffic to automatically document the API structures of websites and applications. It functions as an HTTP traffic capturer and browser-based documentation tool, mapping real-time network requests into standardized API specifications. The tool enables API reverse engineering by intercepting outbound HTTP traffic and using heuristic-based merging to combine headers, bodies, and parameters from multiple requests into unified endpoint definitions. These captured definitions can be visualized as huma

Pyppeteer is a Python library for controlling Chromium-based browsers using the Chrome DevTools Protocol. It functions as a headless browser automation tool, allowing for the programmatic navigation of web pages and the extraction of data from dynamic websites. The project provides low-level browser control through direct communication with the Chrome DevTools Protocol, enabling the interception and modification of network traffic. It differentiates itself by offering specialized performance profiling capabilities, including the measurement of JavaScript and CSS code coverage and the capture

FeHelper is a web browser extension toolbox and frontend development toolkit integrated into Chrome, Firefox, and Edge. It serves as a data transformation utility, a web page debugging tool, and an AI-powered coding assistant. The project distinguishes itself by integrating local models and OpenAI-compatible APIs to write, refactor, and repair code directly within the browser. It also provides capabilities for generating TypeScript schemas and Zod definitions from data samples using AI. The toolkit covers a broad range of developer utilities, including network debugging for HTTP and WebSocke

Livewire is a full-stack framework for PHP that enables the development of reactive, dynamic user interfaces using server-side classes and templates. By bridging the gap between server-side logic and client-side DOM updates, it allows developers to build interactive web applications without writing custom JavaScript. The framework operates as a component-based library, where modular units encapsulate interface logic, state, and event handling directly on the server. The framework distinguishes itself through a reactive architecture that automatically synchronizes state between the browser and

This project is a pre-configured development environment and boilerplate for building Chrome extensions using React and Webpack. It provides a structured project layout and a build system designed to bundle content scripts and background pages into a browser-ready manifest format. The toolkit emphasizes development speed and code quality through a hot reloading system that automatically refreshes the browser upon saving source files. It integrates TypeScript to provide static type definitions for browser extension APIs, ensuring type safety and intelligent code completion during development.

This project is an ad-blocking browser extension that filters web requests and page content to remove advertisements and tracking scripts from websites. It functions as a web content filter, a privacy protection tool, and an element hiding utility. The extension distinguishes itself through a combination of a rule-set evaluation engine and a manual element hiding utility, allowing for the removal of visual clutter and the customization of website layouts. It also provides security through malicious site blocking and adult content restriction. The broader capability surface includes web track

BewlyBewly is a browser extension that customizes the Bilibili homepage, modifying its layout and appearance to deliver a personalized browsing experience without altering the core functionality of the site. It functions as a frontend customization utility, injecting custom CSS and scripts directly into the page context to override default styles and dynamically reapply changes as content loads. The extension is built as a Manifest V3 Chrome extension, using a content script injection system and a DOM mutation observer to ensure customizations persist even as the page updates. It includes a u

Userscripts is a Safari browser extension that installs and runs custom JavaScript and CSS on websites through Apple's content script injection system. It provides a privileged execution context that allows userscripts to perform cross-origin HTTP requests and access clipboard functionality beyond standard browser sandbox restrictions. The extension uses metadata tags like @match, @run-at, and @weight to control precisely when and where scripts execute on web pages. It includes a built-in code editor with syntax highlighting and linting for modifying scripts directly, and supports automatic s

Dexie.js is a wrapper library for IndexedDB that provides a simplified interface for managing and querying structured data within the browser. It functions as a browser database manager used to maintain persistent application state and store binary blobs and records. The project serves as an offline-first data store that synchronizes browser data with remote servers to maintain consistency across sessions. It also acts as a reactive database store by monitoring data changes in real time to trigger automatic user interface updates, and functions as a client-side search engine for indexing and

This project is a collection of community-developed plugins and a modular framework designed to extend the functionality of the Jupyter notebook environment. It serves as a customization tool that modifies the browser-based workspace through a system of injected scripts, stylesheets, and interactive components. The framework manages the lifecycle and registration of independent interface components using metadata-driven configuration. This allows users to enable or disable specific tools via a configuration menu to tailor the workspace without modifying the core application source code. The

This project is a browser extension reading assistant and speed reading tool. It functions as a web accessibility interface that modifies the appearance of text on websites to help users skim content more quickly and reduce eye strain. The tool implements bionic reading acceleration by bolding the initial parts of words to create visual anchors. Users can customize this experience by adjusting fixation strength, word intervals, and visual styling such as colors and opacity. The software covers broad reading enhancement capabilities, including layout management for line height and dark mode,

PT-Plugin-Plus is a browser extension for torrenting that provides tools for private tracker automation, client integration, and site interface modification. It serves as a toolkit for managing torrent downloads, monitoring seed status, and automating repetitive tasks associated with private trackers. The system integrates directly with BitTorrent clients to send files from web pages to connected download clients with a single click. It features movie database integration, allowing users to find media across multiple sites using IMDb IDs or integrated search triggers. The project covers mult

Mock is a JavaScript API mocking tool and network request interceptor designed to decouple front-end development from back-end progress. It functions as an API simulation tool and mock data generator, allowing developers to build user interfaces and high-fidelity prototypes by mimicking the request and response cycle without a live server. The system provides a mechanism for intercepting outgoing HTTP calls and returning simulated data. It enables front-end prototyping by generating synthetic datasets to validate application behavior during automated testing cycles and development. Capabilit

ChatGPT-Shortcut is a prompt engineering toolkit and management library designed to organize, refine, and deploy structured instructions for large language models. It functions as a browser-based prompt injector and a self-hosted prompt database, allowing users to maintain a curated collection of specialized templates. The project features a community prompt gallery where users can publish, discover, and vote on effective templates. It distinguishes itself by integrating these libraries directly into chat interfaces via userscripts or browser extensions, enabling access to prompts through sid

jsdom is a Node.js implementation of web standards that functions as a headless browser emulator. It provides a JavaScript execution environment and an HTML and XML parser to simulate a browser environment on the server side, implementing various web APIs and W3C standards. The project distinguishes itself by providing a sandboxed runtime for executing scripts embedded in HTML or external files. It includes specialized polyfills for the Canvas API and manages session state through HTTP cookie management. Its broader capabilities cover network interaction via request interception and resource

Home Assistant is a local home automation platform and server that acts as an IoT device orchestrator. It integrates diverse smart home hardware by wrapping third-party APIs into a standardized logic layer and stores all system state and historical statistics on local hardware to eliminate cloud dependencies. The system functions as a Matter IoT controller and an MQTT home automation bridge, allowing for local interoperability between different manufacturers. It features a state-based entity model and an internal event bus that decouple physical device logic from system automation. The platf

Supermium is a Chromium-based web browser backported to run on legacy versions of Windows. It uses an abstraction layer to adapt modern engine requirements, enabling contemporary web browsing on older operating systems that lack native support for current Chromium versions. The project integrates content decryption modules to allow the playback of DRM-protected media streams on unsupported platforms. It also features the ability to disable machine-specific encryption, allowing user profiles to be portable across different hardware installations. The browser includes a functional sandbox to i

Nightmare is an Electron-based browser automation library and headless browser controller. It provides the infrastructure to programmatically navigate web pages, interact with DOM elements, and execute JavaScript within a background browser instance. The project distinguishes itself by integrating a full Chromium instance within an Electron shell, allowing for the management of browser sessions, network proxy settings, and persistent storage partitions. It enables the capture of page states as PNG screenshots, PDF documents, or HTML files. The tool covers a broad range of capabilities includ

Bromite is a privacy-focused fork of the Chromium browser for Android that blocks advertisements and tracking scripts by default, enforces encrypted HTTPS connections, and prevents browser fingerprinting without requiring any extensions or manual configuration. It applies a patch-based build system to layer privacy and security modifications directly onto the upstream Chromium codebase during compilation, integrating a filter list engine for network-level ad blocking and adding noise to browser APIs to mask device identity. The browser distinguishes itself through comprehensive privacy harden