Address Variants

Checksummed, Lowercase, and Uppercase branded address types

Try it Live

Run Address examples in the interactive playground

Address Variants

Branded hex string types representing different address formats with compile-time guarantees.

Overview

Address variants provide type-safe hex strings with specific casing guarantees:

• Checksummed - EIP-55 mixed-case format for display and verification
• Lowercase - All lowercase hex for canonical storage
• Uppercase - All uppercase hex for specific protocols

Each variant is a branded hex string type extending Hex.Sized<20>, not a Uint8Array.

ChecksumAddress

EIP-55 checksummed address format with mixed casing based on keccak256 hash.

Address.Checksummed.from(addr)

Create checksummed hex string from Address.

const addr = Address("0x742d35cc6634c0532925a3b844bc9e7595f51e3e")

// Get checksummed string
const checksummed = Address.Checksummed(addr)
// "0x742d35Cc6634C0532925a3b844Bc9e7595f51e3e" (mixed case)

// Type is branded Checksummed, not AddressType
typeof checksummed // "string"

Parameters:

• addr: AddressType - Address to checksum

Returns: Checksummed - Branded checksummed hex string

Type:

import type { Hex } from 'tevm'

type Checksummed = Hex.Sized<20> & {
  readonly __variant: 'Address'
  readonly __checksummed: true
}

Defined in: primitives/Address/AddressType/ChecksumAddress.js:23

Note: Uses keccak256 internally.

Address.Checksummed.isValid(str)

Validate EIP-55 checksum of address string.

// Valid checksummed
Address.Checksummed.isValid("0x742d35Cc6634C0532925a3b844Bc9e7595f51e3e") // true

// Invalid checksum (wrong casing)
Address.Checksummed.isValid("0x742d35cc6634c0532925a3b844bc9e7595f51e3e") // false
Address.Checksummed.isValid("0x742D35CC6634C0532925A3B844BC9E7595F51E3E") // false

// All lowercase/uppercase passes (no mixed case = no checksum)
Address.Checksummed.isValid("0x742d35cc6634c0532925a3b844bc9e7595f51e3e") // true
Address.Checksummed.isValid("0x742D35CC6634C0532925A3B844BC9E7595F51E3E") // true

Parameters:

• str: string - Address string to validate

Returns: boolean

Defined in: primitives/Address/AddressType/ChecksumAddress.js:55

EIP-55 Logic:

• If all letters same case (all lower or all upper), valid
• If mixed case, each letter’s case must match keccak256-based checksum

LowercaseAddress

All lowercase hex format for canonical representation.

Address.Lowercase.from(addr)

Create lowercase hex string from Address.

const addr = Address("0x742D35CC6634C0532925A3B844BC9E7595F51E3E")

const lowercase = Address.Lowercase(addr)
// "0x742d35cc6634c0532925a3b844bc9e7595f51e3e"

Parameters:

• addr: AddressType - Address to convert

Returns: Lowercase - Branded lowercase hex string

Type:

import type { Hex } from 'tevm'

type Lowercase = Hex.Sized<20> & {
  readonly __variant: 'Address'
  readonly __lowercase: true
}

Defined in: primitives/Address/AddressType/LowercaseAddress.js:20

UppercaseAddress

All uppercase hex format.

Address.Uppercase.from(addr)

Create uppercase hex string from Address.

const addr = Address("0x742d35cc6634c0532925a3b844bc9e7595f51e3e")

const uppercase = Address.Uppercase(addr)
// "0x742D35CC6634C0532925A3B844BC9E7595F51E3E"

Parameters:

• addr: AddressType - Address to convert

Returns: Uppercase - Branded uppercase hex string

Type:

import type { Hex } from 'tevm'

type Uppercase = Hex.Sized<20> & {
  readonly __variant: 'Address'
  readonly __uppercase: true
}

Defined in: primitives/Address/AddressType/UppercaseAddress.js:20

Variant Comparison

Variant	Casing	Use Case	Keccak256 Needed
Checksummed	Mixed	Display, verification	Yes
Lowercase	All lower	Canonical storage, comparison	No
Uppercase	All upper	Specific protocols	No