PolkaSub - A Subscription Manager on Polkadot Westend

A subscription management system built on the Polkadot Westend Asset Hub testnet. Built for convenience, transparency, simplicity, and security. EasyA x Polkadot hackathon at Havard University 2025.

Demo

Video demo:

Presentation: https://www.loom.com/share/7abb1d115cb448d59292ff0a16ccc0ce?sid=82d11bbf-aa8d-4ae0-b046-9ebaf0cb79c2

Live demo: https://www.loom.com/share/18f0fa1686b04e17bc8312bea70ee96e?sid=c41504c0-daa0-4532-b24f-42246e5da9c8

Screenshots of the frontend:

Canvas presentation link:

https://www.canva.com/design/DAGl1CHQT-w/7DdAlb1r3PYss-N1VcxO2g/edit?utm_content=DAGl1CHQT-w&utm_campaign=designshare&utm_medium=link2&utm_source=sharebutton

Features

Frontend

• Built with typescript and nextjs
• Metamask for wallet connection
• UI:
  • View active subscriptions
  • Create new subscriptions
  • Check payment history and progress
  • Cancel subscriptions

Smart Contract (Solidity)

• Manages subscription agreements
• Collects and transfers payments
• Tracks subscription status (Active, Cancelled, Expired)
• block explorer link (asset hub westend subscan): https://assethub-westend.subscan.io/account/0x455aaFbD12cAeF26858ecd72c87f944Ce1f04d64

Full desription

PolkaSub is a decentralized platform that allows users to create, manage, and cancel recurring subscription payments directly on-chain. It removes reliance on traditional payment processors, offers full transparency into payment schedules, and ensures user control over subscription services — all powered by crypto assets on the Westend Asset Hub. Flow: Users create subscriptions by interacting directly with a smart contract. Subscription payments are scheduled transparently based on dates or block intervals. Cancellations are instant, with no need for provider approval. Developers and providers can easily integrate subscription models into their services. Advantages: Interoperability: Future expansion to subscriptions across parachains. Scalability: Frequent payment interactions remain low-cost. Security: Shared security through Polkadot relay chain governance.

Project Structure

• /contract - Hardhat project with Solidity smart contracts for subscription management
• /frontend - Next.js frontend application

Setup and Installation

1. Navigate to the frontend directory:

   cd frontend

2. Install dependencies:

   npm install --legacy-peer-deps

3. Start the development server:

   npx next build

   npx next dev

4. Access the application at http://localhost:3000

Important notes for users

• Make sure your wallet is on the Westend Asset Hub network (chainId: 420420421)
• Fund your deployer's account with some test WND

Important notes for hackathon

• Parts of the current integration with frontend and smart contract are still in development, not all features are working as intended.

Future Improvements

• Ability to delete a subscription
• Deploy to mainnet
• Make frontend prettier
• Fix bugs in function calls