License

Type-safe SPDX license identifiers for smart contract metadata.

Overview

Branded string type representing SPDX license identifiers. Used in Solidity source files and smart contract metadata to identify licensing terms. Includes validation for OSI-approved licenses.

Quick Start

Basic Usage
Common Licenses
Solidity Usage

import * as License from '@tevm/voltaire/License'

// Create license identifier
const mit = License.from("MIT")
const apache = License.from("Apache-2.0")
const unlicensed = License.from("UNLICENSED")

// Convert to string
License.toString(mit)  // "MIT"

// Check OSI approval
License.isOSI("MIT")        // true
License.isOSI("Apache-2.0") // true
License.isOSI("UNLICENSED") // false

import { COMMON_LICENSES, OSI_APPROVED_LICENSES } from '@tevm/voltaire/License'

// Common SPDX identifiers
COMMON_LICENSES
// ["MIT", "Apache-2.0", "GPL-3.0", "GPL-2.0", "LGPL-3.0",
//  "BSD-3-Clause", "BSD-2-Clause", "ISC", "MPL-2.0", "UNLICENSED"]

// OSI-approved licenses
OSI_APPROVED_LICENSES
// ["MIT", "Apache-2.0", "GPL-3.0", "GPL-2.0", "LGPL-3.0",
//  "LGPL-2.1", "BSD-3-Clause", "BSD-2-Clause", "ISC",
//  "MPL-2.0", "AGPL-3.0", "EPL-2.0", "CC0-1.0"]

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract MyContract {
    // Contract code
}

import * as License from '@tevm/voltaire/License'

// Parse license from Solidity source
const source = `// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;`

const match = source.match(/SPDX-License-Identifier:\s*(\S+)/)
if (match) {
  const license = License.from(match[1])
  console.log(License.isOSI(license))  // true
}

Common Licenses

License	OSI Approved	Description
MIT	Yes	Permissive, minimal restrictions
Apache-2.0	Yes	Permissive with patent grant
GPL-3.0	Yes	Strong copyleft
GPL-2.0	Yes	Strong copyleft (earlier version)
LGPL-3.0	Yes	Weak copyleft for libraries
BSD-3-Clause	Yes	Permissive with attribution
BSD-2-Clause	Yes	Simplified BSD
ISC	Yes	Simplified BSD-like
MPL-2.0	Yes	Weak copyleft file-level
AGPL-3.0	Yes	Strong copyleft + network use
UNLICENSED	No	Proprietary/no license

API Reference

Constructors

import * as License from '@tevm/voltaire/License'

// Create from SPDX identifier
const license = License.from("MIT")

Methods

import * as License from '@tevm/voltaire/License'

const license = License.from("Apache-2.0")

// Convert to string
License.toString(license)  // "Apache-2.0"

// Check if OSI-approved
License.isOSI(license)     // true
License.isOSI("GPL-3.0")   // true
License.isOSI("UNLICENSED") // false

Constants

import { COMMON_LICENSES, OSI_APPROVED_LICENSES } from '@tevm/voltaire/License'

// Common SPDX license identifiers
COMMON_LICENSES: string[]

// OSI-approved open source licenses
OSI_APPROVED_LICENSES: string[]

Solidity License Identifier

SPDX license identifiers are required in Solidity files since version 0.6.8:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

The identifier appears in compiled contract metadata and can be used to:

Identify licensing terms programmatically
Filter contracts by license type
Ensure compliance with open source requirements

Use Cases

Contract Metadata Analysis

import * as License from '@tevm/voltaire/License'

interface ContractMetadata {
  license: string
  compiler: string
  source: string
}

function analyzeContract(metadata: ContractMetadata) {
  const license = License.from(metadata.license)

  return {
    license: License.toString(license),
    isOpenSource: License.isOSI(license),
    isPermissive: ["MIT", "Apache-2.0", "BSD-3-Clause"].includes(
      License.toString(license)
    )
  }
}

License Filtering

import * as License from '@tevm/voltaire/License'
import { OSI_APPROVED_LICENSES } from '@tevm/voltaire/License'

interface Contract {
  address: string
  license: string
}

function filterOpenSourceContracts(contracts: Contract[]): Contract[] {
  return contracts.filter(c => License.isOSI(c.license))
}

function filterByLicense(contracts: Contract[], allowed: string[]): Contract[] {
  return contracts.filter(c => allowed.includes(c.license))
}

// Only permissive licenses
const permissive = filterByLicense(contracts, ["MIT", "Apache-2.0", "BSD-3-Clause"])

SPDX License List - Full list of SPDX identifiers
OSI Approved Licenses - Open Source Initiative

References

SPDX Specification - SPDX license format
Solidity License Identifiers - Solidity documentation

​License

​Overview

​Quick Start

​Common Licenses

​API Reference

​Constructors

​Methods

​Constants

​Solidity License Identifier

​Use Cases

​Contract Metadata Analysis

​License Filtering

​Related

​References