Bitcoin-Backed NFT Marketplace with DeFi Elements

A decentralized NFT marketplace smart contract built on Stacks, featuring NFT minting with Bitcoin collateralization, fractional ownership, staking capabilities, and DeFi elements.

Features

Core NFT Functionality

• Mint NFTs with Bitcoin (STX) collateral backing
• Transfer NFTs between wallets
• Minimum collateral ratio of 150% required for minting
• URI validation for NFT metadata

Marketplace

• List NFTs for sale with custom pricing
• Purchase NFTs with automatic fee distribution
• 2.5% protocol fee on all transactions
• Built-in overflow protection for mathematical operations

Fractional Ownership

• Split NFT ownership into transferable shares
• Track share distribution across multiple owners
• Transfer shares between wallets with balance validation

Staking Mechanism

• Stake NFTs to earn yield
• 5% annual yield rate
• Accumulated rewards calculation based on block height
• Claim rewards in STX tokens
• Unstake with automatic reward distribution

Technical Details

Constants

min-collateral-ratio: 150%
protocol-fee: 2.5% (25 basis points)
yield-rate: 5% annually (50 basis points)

Error Codes

• u100: Owner-only operation
• u101: Not token owner
• u102: Insufficient balance
• u103: Invalid token
• u104: Listing not found
• u105: Invalid price
• u106: Insufficient collateral
• u107: Already staked
• u108: Not staked
• u109: Invalid percentage
• u110: Invalid URI
• u111: Invalid recipient
• u112: Overflow error

Usage

Minting an NFT

(contract-call? .nft-marketplace mint-nft "https://example.com/metadata.json" u1000)

Listing an NFT

(contract-call? .nft-marketplace list-nft u1 u5000)

Purchasing an NFT

(contract-call? .nft-marketplace purchase-nft u1)

Staking Operations

;; Stake NFT
(contract-call? .nft-marketplace stake-nft u1)

;; Unstake NFT
(contract-call? .nft-marketplace unstake-nft u1)

Fractional Ownership

(contract-call? .nft-marketplace transfer-shares u1 'SP2J6ZY48GV1EZ5V2V5RB9MP66SW86PYKKNRV9EJ7 u50)

Security Considerations

1. Collateral Protection

   • All NFTs must maintain minimum collateral ratio
   • Collateral is locked in contract until NFT is burned or transferred

2. Access Control

   • Owner-only functions for critical operations
   • Token ownership verification for transfers and listings
   • Contract self-calls prevented for sensitive operations

3. Mathematical Safety

   • Overflow checking on all mathematical operations
   • Safe addition implementation for balance updates
   • Percentage calculations use basis points for precision

Query Functions

Read-Only Operations

• get-token-info: Retrieve token details
• get-listing: Get active listing information
• get-fractional-shares: Query share ownership
• get-staking-rewards: Check accumulated rewards
• calculate-rewards: Preview pending staking rewards

Development

Prerequisites

• Clarity contract deployment environment
• Access to Stacks blockchain
• Understanding of Bitcoin and STX token mechanics

Testing

Recommended test coverage should include:

• NFT minting with various collateral ratios
• Marketplace operations with edge cases
• Staking reward calculations
• Fractional ownership transfers
• Error condition handling

License

This smart contract is provided underunder the MIT License. See the LICENSE file for details.

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Note: This is a complex smart contract handling real value. Thorough audit and testing are strongly recommended before mainnet deployment.