Subis

zkSync ( Native AA ) Decentralized Subscription Service with Gasless Payments

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Subis - Decentralized Subscriptions with Gasless & Automated Payments ( zkSync Native AA and Price Feeds )

Inspiration

As a developer who regularly works with centralized payment technologies, I've witnessed firsthand the challenges businesses face when relying on centralized subscription management services:

  • High fees
  • Risk of account blocking
  • Limited control over funds

These hurdles hinder growth and flexibility. This realization led to a vision in my head for the inspiration for Subis, which I saw as a decentralized, transparent, and cost-effective solution that would put the power back in the hands of businesses. At the same time, it would provide subscribers with a seamless and gasless experience through Native AA on zkSync. So, I took it up as a challenge to solve this problem.

What it does

Subis is built as a comprehensive subscription management solution that empowers businesses to:

  • Create, manage, and automate their subscription plans effortlessly
  • Set up monthly subscriptions
  • Share a single link for users to subscribe and access services
  • Have complete control over their plans
  • Create and edit subscription plans
  • Set prices in USD
  • Sponsor and enable the gasless creation of smart accounts for subscribers
  • Enable gasless subscriptions
  • Automate charges
  • Allow subscribers to switch plans seamlessly with proration

By leveraging smart contracts, subscription data is securely stored on-chain, providing reliability and transparency. Integrating Subis into existing applications was designed to be quick and easy, allowing businesses to enable and manage subscriptions effortlessly using the on-chain data.

How I built it

Subis is built on the zkSync network, using the power of:

  • zkSync's Native Account Abstraction (AA)
  • Chainlink Price Feeds

Native AA allows for the creation of smart contract wallets that enable advanced functionalities like:

  • Gasless transactions
  • Daily spending limits in USD
  • Automated charges

This eliminates the limitations of traditional accounts and provides a more user-friendly experience for subscribers.

To ensure accurate and reliable pricing, I integrated Chainlink Price Feeds, which provide accurate USD prices directly on-chain. This enables businesses to set subscription plan prices in USD and automatically convert them to the equivalent amount of tokens based on real-time exchange rates. By basing itself on Chainlink's infra, Subis ensures high reliability of the pricing data.

Challenges I ran into

For executing transactions from the subscriber's smart account wallet, one significant challenge was figuring out how to handle EIP-712 transactions through the front end. EIP-712 is a standard for typed structured data hashing and signing, crucial for signing messages off-chain and executing transactions through smart contract wallets. With limited examples and documentation, I had to dive deep into the EIP-712 signer class to properly implement it in Subis. Finally, I figured it out after 2 days of tinkering around with the internal code of the class and I felt super happy about that, to the point that I screamed in my room after solving it and making EIP712 transactions through Smart Accounts work, haha.

Accomplishments that I'm proud of

I'm incredibly proud of building an end-to-end solution for decentralized subscription management in a short timeframe. Despite the complexities, I was able to make use of the capabilities of zkSync and Chainlink to create a functional platform.

  • I dedicated the first 20 days to thoroughly studying the underlying technologies, being new to account abstraction I studied ERC 4337 in depth in the early days of the hackathon.
  • Through Patrick Collins' 10-hour long lectures on Foundry, I gained knowledge about Chainlink.
  • In the final 10 days, I utilized this knowledge to develop and deliver a working project, making the practical implementation of these cutting-edge technologies I spent time learning.

What I learned

Through the development of Subis:

  • I gained valuable insights into Native Account Abstraction and its transformative potential.
  • I discovered the power of smart contract wallets and how they can fully change the current paradigm of how the user interacts with decentralized applications.
  • I explored Chainlink Price Feeds for the first time and understood how decentralized sources of truth can be seamlessly integrated into smart contracts, enabling intuitive and user-friendly pricing mechanisms.

What's next for Subis

As zkSync evolves, I am truly excited about the future prospects of Subis:

  • I look forward to integrating Chainlink Automation to replace the centralized cron job with decentralized automation, further enhancing the platform's decentralization and reliability.
  • I also look forward to integrating yearly, quarterly, half-yearly duration flexibility for plans ( as of now subis has only monthly subscription support )
  • I see great potential in applying Subis to real-world scenarios, such as SaaS platforms or freelance service marketplaces, and witnessing its impact on subscription management and user experience.

On a personal level, the development of Subis has been an incredible learning experience, and I am eager to continue expanding my knowledge and skills in the realm of decentralized technologies. I believe that the combination of zkSync's Native Account Abstraction and Chainlink's decentralized oracle network holds immense promise, and I am excited to contribute further to this ecosystem.

Deployed Contracts

The Subis contracts are currently deployed on the zkSync Sepolia testnet. Here are the contract addresses:

  • AA Factory: 0xcEa62E27DA26129CDAB1784Ea59F9ae4a39DdcE8
  • Manager Factory: 0x6367daDA707E978c3a050C74C5f1cC51001b0066

You can interact with these contracts using the zkSync Sepolia testnet and the provided addresses.

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