Subra

Subra is a decentralized subscription manager on Starknet. It lets creators launch on-chain subscription plans in seconds and users manage all their recurring payments in one transparent dashboard.

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Inspiration

Subra was inspired by the frustration of fragmented, centralized subscription systems that lock users into opaque recurring payments. We wanted to reimagine subscriptions as transparent, user-owned, and automated through smart contracts.

What it does

We built Subra on Starknet, leveraging Cairo smart contracts, a Factory + Subscription contract architecture, and keepers for automated on-chain renewals. The frontend provides creators and users with a clean dashboard to manage all plans and payments seamlessly.

How we built it

During development, we learned how to coordinate multiple contract layers, integrate auto-renewal logic using off-chain keepers, and optimize event indexing for scalability.

Challenges we ran into

The biggest challenges were designing gas-efficient recurring payments, managing on-chain user state, and ensuring secure authorization for automated renewals — all while keeping the UX simple and intuitive.

Accomplishments that we're proud of

We built a fully functional decentralized subscription system from scratch on Starknet, featuring a factory-based contract architecture, automated renewals via keepers, and an intuitive dashboard for both creators and users. We’re proud that Subra turns complex on-chain payment logic into a simple, real-world user experience — a true Stripe for Web3.

What we learned

We deepened our understanding of Cairo smart contract design, especially around secure recurring payments, modular contract architecture, and event-driven indexing. We also learned how to integrate off-chain automation (keepers) into a decentralized workflow and how important UX is when abstracting away blockchain complexity for non-technical users.

What's next for Subra

We plan to expand Subra into a full subscription protocol for the Starknet ecosystem — adding multi-token support, cross-chain integrations, analytics for creators, and open APIs for dApps and SaaS tools. We also aim to collaborate with creators, guilds, and Web3 platforms to make Subra the standard for recurring payments in Web3.

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