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What is SubWallet Extension?

SubWallet Extension is a browser extension wallet forked from polkadot-js/extension, designed to support multiple blockchain networks while maintaining the ability to rebase with the polkadot-js origin at any time. It provides a comprehensive solution for managing crypto assets across different chains within a browser environment.

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Technical Perspective

SubWallet Extension is built as a multi-package monorepo that follows Chrome Extension architecture patterns. The extension operates across three main execution contexts:
  • Background environment - Handles message passing, state management, and API calls
  • Extension UI - React-based frontend for popup and portfolio views
  • Inject scripts - Scripts injected into web pages to enable dapp interactions
All data requests are centralized through the background environment. Extension pages and inject scripts consume data from the background without making direct API calls, ensuring consistent state management and security.

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Tech Stack

SubWallet Extension is built with the following core technologies:

TypeScript

Fully typed codebase for better developer experience and code safety

React

UI components built with React and Redux Toolkit for state management

Polkadot.js

Core blockchain interaction libraries from the Polkadot ecosystem

Webpack

Module bundler for compiling the extension for different browsers

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Key Dependencies

  • @polkadot/api (^16.4.2) - Blockchain API interactions
  • @subwallet/chain-list (0.2.124) - Multi-chain support definitions
  • Redux Toolkit - State management with react hooks
  • RxJS (^7.8.1) - Reactive programming for subscriptions
  • Dexie (^3.2.2) - IndexedDB wrapper for local storage
  • bitcoinjs-lib (6.1.5) - Bitcoin protocol support

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Architecture Overview

Main Concept The extension consists of three primary components:
  1. Background Environment - Core processing engine
  2. Extension Pages - User-facing interfaces
  3. Inject Scripts - Dapp integration layer
For detailed architecture information, see the Architecture page.

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What Can Developers Build?

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Extension Development

Developers can extend SubWallet’s functionality by:
  • Adding new blockchain network support
  • Implementing custom API integrations
  • Creating new storage stores for persistent data
  • Building custom cronjobs for background tasks
  • Adding new UI components and pages

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Dapp Integration

Dapp developers can integrate with SubWallet to:
  • Connect to user wallets via the injected provider
  • Request account access and signatures
  • Interact with multiple blockchain networks
  • Leverage MetaMask compatibility mode

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Available Packages

Core features running in background: API calls, data persistence, and script injection
Convenience wrapper for dapps to work with injected objects and simplify integration
Wrapper allowing extension developers to inject their extension for dapp use
Chain definitions and stripped-down metadata formats for supported networks
Custom package extending extension-base with SubWallet-specific features
React UI components for the extension popup and portfolio views
Main entry point containing injection and background processing logic
MetaMask compatibility layer for EVM chain support

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Development Workflow

SubWallet Extension uses modern development practices:
  • Monorepo structure with Yarn workspaces
  • Automated testing with Jest
  • Code quality enforced with ESLint
  • CI/CD with GitHub Actions for automated builds
  • Internationalization support with i18next

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Getting Started

Ready to start developing? Head over to the Setup Guide to get your development environment configured.

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Resources

GitHub Repository

View the source code and contribute

Report Issues

Submit bugs and feature requests

Architecture Guide

Deep dive into the extension architecture

Setup Guide

Get your development environment ready

Build docs developers (and LLMs) love

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