Grass

Grass is a fitness platform that turns your real world activity into verified onchain achievements. It combines health tracking, social challenges, and incentives to help users stay active and connected. Using zero knowledge, Grass verifies fitness data like steps, distance, and heart rate without revealing sensitive information.

The platform encourages users to “touch grass” by proving their progress and health scores. Communities can form around shared goals, and users can place social bets on their friends training targets.

Grass uses:

• zkTLS to verify real fitness data
• Blockscout Merits to reward user activity
• Smart contracts that manage bets, profiles, and communities
• Integration with the vlayer SDK for private web proof verification
• Ethereum for secure settlement

Whether you want to challenge friends, join a fitness tribe, or simply stay motivated, Grass makes your activity count, literally.

We combined TypeScript, Solidity, and zero knowledge proof tooling. The architecture is split into the following components:

• Next.js Frontend: React based interface for tracking fitness, joining communities, and placing social bets
• Solidity Smart Contracts: Handle fitness verification, betting logic, and community requirements
• Web Proof System (via vlayer SDK): Enables private fitness data verification using zkTLS

The smart contract suite includes:

• WebProofVerifier: Verifies cryptographic proofs of fitness data, manages user profiles and betting logic
• WebProofProver: Generates zero knowledge proofs from real world fitness metrics

The frontend stack includes:

• reown + Wagmi + Viem: For Ethereum wallet connectivity and contract interaction
• vlayer Client SDK – For submitting fitness proofs and web-based attestation
• Daisy UI + Tailwind CSS: For responsive and clean UI

We also incentivize the user activity giving them Blockscout Merits.

Grass turns physical activity into verified, onchain secure, social, and incentivized.