SYNCRO

Syncro is a self-custodial, cross-chain subscription automation system that helps users manage and pay for online services without relying on banks or Web2 billing apps. Users connect a wallet, import subscriptions automatically or add them manually, set spending limits, and receive early reminders before each renewal.

Because most digital services only accept Visa/Mastercard, Syncro does not attempt to pay merchants directly with tokens. Instead, it uses a local autonomous agent that periodically funds the user’s crypto-issued debit card (e.g., Mastercard/Visa cards from Ready or Pexx) just before each renewal. The user approves limits once, and the agent handles everything else.

Syncro is powered by LayerZero to allow users to deposit USDC from any chain and have their subscription vault synchronized and spendable on any supported network. All subscription data, logs, and notifications are stored using Protocol Labs’ decentralized storage stack, ensuring user privacy, portability, and censorship resistance.

The result is a self-custodial, chain-agnostic subscription manager that prevents silent price hikes, stops unwanted renewals, and ensures crypto users never lose track of the services they pay for. Syncro brings “smart subscriptions” to Web3 using decentralized agents, omnichain payments, and real crypto cards.

Syncro is built as a lightweight, self-custodial subscription engine that connects a user’s wallet, a cross-chain vault, and a crypto card top-up agent. The frontend is built in Next.js + Tailwind, connected to a simple JSON-based subscription schema where users can import or manually add their services.

We built a cross-chain “subscription vault” using LayerZero, allowing users to deposit USDC from any chain. LayerZero’s messaging lets us sync balances and allow the local agent to read the user’s approved spending limit without requiring them to bridge manually.

A small backend agent (Node.js) runs a scheduler that reads subscription metadata from Filecoin/IPFS, which we use for decentralized storage of subscription data, logs, and notifications. This ensures that Syncro does not depend on centralized databases.

The agent never holds user funds. Instead, it monitors upcoming renewals, checks the user’s approved limit, and triggers a card top-up transaction to a crypto-issued Mastercard/Visa (e.g., Ready). Once funded, the card handles the merchant payment in the traditional system.

We also implemented safeguards like “spending ceilings,” “price-change alerts,” and “N-day reminders.” The hacky—but effective—part is the card-funding simulation: since most merchants don’t accept stablecoins, we used a proxy contract to simulate card-funding flows while still demonstrating the agent logic, LayerZero sync, and Filecoin persistence.

Overall, Syncro pieces together omnichain payments, decentralized storage, and real-world card rails to demonstrate a functional, self-custodial subscription manager for crypto users.