Vesting Schedules

Vesting schedules are mechanisms used in blockchain projects to release tokens to team members, investors, or other stakeholders over a specified period. This approach helps align incentives, prevent immediate sell-offs, and promote long-term commitment to the project.

Understanding Vesting Schedules

A vesting schedule dictates how and when tokens are released to a recipient. Common elements include:

Cliff Period: An initial period during which no tokens are vested.
Vesting Period: The total duration over which tokens are gradually released.
Release Interval: The frequency at which tokens are released (e.g., monthly, quarterly).
Total Allocation: The total number of tokens to be vested.

Types of Vesting Schedules

Linear Vesting: Tokens are released uniformly over the vesting period.
Graded Vesting: Tokens vest in portions at different intervals.
Cliff Vesting: All or a significant portion of tokens vest after the cliff period.

Implementing Vesting Schedules in Solidity

Smart contracts can automate vesting schedules, ensuring transparency and trustlessness. Below is an example of a simple Solidity contract implementing a linear vesting schedule.

Example Solidity Contract

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
 
contract TokenVesting {
    address public beneficiary;
    uint256 public start;
    uint256 public duration;
    uint256 public cliff;
    uint256 public totalTokens;
    uint256 public released;
 
    IERC20 public token;
 
    constructor(
        address _token,
        address _beneficiary,
        uint256 _start,
        uint256 _cliffDuration,
        uint256 _duration,
        uint256 _totalTokens
    ) {
        require(_beneficiary != address(0), "Invalid beneficiary");
        require(_cliffDuration <= _duration, "Cliff longer than duration");
        require(_duration > 0, "Duration must be > 0");
 
        token = IERC20(_token);
        beneficiary = _beneficiary;
        start = _start;
        cliff = _start + _cliffDuration;
        duration = _duration;
        totalTokens = _totalTokens;
    }
 
    function release() public {
        require(block.timestamp >= cliff, "Cliff period not reached");
        uint256 unreleased = releasableAmount();
        require(unreleased > 0, "No tokens to release");
 
        released += unreleased;
        token.transfer(beneficiary, unreleased);
    }
 
    function releasableAmount() public view returns (uint256) {
        return vestedAmount() - released;
    }
 
    function vestedAmount() public view returns (uint256) {
        if (block.timestamp < cliff) {
            return 0;
        } else if (block.timestamp >= start + duration) {
            return totalTokens;
        } else {
            return (totalTokens * (block.timestamp - start)) / duration;
        }
    }
}
 
interface IERC20 {
    function transfer(address recipient, uint256 amount) external returns (bool);
}

Understanding Vesting Schedules

Types of Vesting Schedules

Implementing Vesting Schedules in Solidity

Example Solidity Contract

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