diff --git a/src/Siwe.ts b/src/Siwe.ts
new file mode 100644
index 00000000..94ec54ce
--- /dev/null
+++ b/src/Siwe.ts
@@ -0,0 +1,19 @@
+export {
+  createSiweMessage as createMessage,
+  createSiweMessage,
+} from './internal/siwe/createSiweMessage.js'
+
+export {
+  generateSiweNonce as generateNonce,
+  generateSiweNonce,
+} from './internal/siwe/generateSiweNonce.js'
+
+export {
+  parseSiweMessage as parseMessage,
+  parseSiweMessage,
+} from './internal/siwe/parseSiweMessage.js'
+
+export {
+  validateSiweMessage as validateMessage,
+  validateSiweMessage,
+} from './internal/siwe/validateSiweMessage.js'
diff --git a/src/index.ts b/src/index.ts
index 0bbf6ddd..0ebed53f 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -10,6 +10,7 @@ export * as Hex from './Hex.js'
 export * as Secp256k1 from './Secp256k1.js'
 export * as Signature from './Signature.js'
 export * as Rlp from './Rlp.js'
+export * as Siwe from './Siwe.js'
 export * as TypedData from './TypedData.js'
 export * as Types from './Types.js'
 export * as Value from './Value.js'
diff --git a/src/internal/errors/siwe.test.ts b/src/internal/errors/siwe.test.ts
new file mode 100644
index 00000000..93ae59ab
--- /dev/null
+++ b/src/internal/errors/siwe.test.ts
@@ -0,0 +1,26 @@
+import { expect, test } from 'vitest'
+
+import { SiweInvalidMessageFieldError } from './siwe.js'
+
+test('SiweInvalidMessageFieldError', () => {
+  expect(
+    new SiweInvalidMessageFieldError({
+      field: 'nonce',
+      metaMessages: [
+        '- Nonce must be at least 8 characters.',
+        '- Nonce must be alphanumeric.',
+        '',
+        'Provided value: foobarbaz$',
+      ],
+    }),
+  ).toMatchInlineSnapshot(`
+    [SiweInvalidMessageFieldError: Invalid Sign-In with Ethereum message field "nonce".
+
+    - Nonce must be at least 8 characters.
+    - Nonce must be alphanumeric.
+
+    Provided value: foobarbaz$
+
+    See: https://oxlib.sh/errors#siweinvalidmessagefielderror]
+  `)
+})
diff --git a/src/internal/errors/siwe.ts b/src/internal/errors/siwe.ts
new file mode 100644
index 00000000..3162e2b5
--- /dev/null
+++ b/src/internal/errors/siwe.ts
@@ -0,0 +1,16 @@
+import { BaseError } from './base.js'
+
+export class SiweInvalidMessageFieldError extends BaseError {
+  override readonly name = 'SiweInvalidMessageFieldError'
+
+  constructor(parameters: {
+    field: string
+    metaMessages?: string[] | undefined
+  }) {
+    const { field, metaMessages } = parameters
+    super(`Invalid Sign-In with Ethereum message field "${field}".`, {
+      docsPath: '/errors#siweinvalidmessagefielderror',
+      metaMessages,
+    })
+  }
+}
diff --git a/src/internal/isUri.test.ts b/src/internal/isUri.test.ts
new file mode 100644
index 00000000..c9c59ccf
--- /dev/null
+++ b/src/internal/isUri.test.ts
@@ -0,0 +1,42 @@
+import { expect, test } from 'vitest'
+
+import { isUri } from './isUri.js'
+
+test('default', () => {
+  expect(isUri('https://example.com/foo')).toMatchInlineSnapshot(
+    `"https://example.com/foo"`,
+  )
+})
+
+test('behavior: check for illegal characters', () => {
+  expect(isUri('^')).toBeFalsy()
+})
+
+test('incomplete hex escapes', () => {
+  expect(isUri('%$#')).toBeFalsy()
+  expect(isUri('%0:#')).toBeFalsy()
+})
+
+test('missing scheme', () => {
+  expect(isUri('example.com/foo')).toBeFalsy()
+})
+
+test('authority with missing path', () => {
+  expect(isUri('1http:////foo.html')).toBeFalsy()
+})
+
+test('scheme begins with letter', () => {
+  expect(isUri('$https://example.com/foo')).toBeFalsy()
+})
+
+test('query', () => {
+  expect(isUri('https://example.com/foo?bar')).toMatchInlineSnapshot(
+    `"https://example.com/foo?bar"`,
+  )
+})
+
+test('fragment', () => {
+  expect(isUri('https://example.com/foo#bar')).toMatchInlineSnapshot(
+    `"https://example.com/foo#bar"`,
+  )
+})
diff --git a/src/internal/isUri.ts b/src/internal/isUri.ts
new file mode 100644
index 00000000..4792d2e4
--- /dev/null
+++ b/src/internal/isUri.ts
@@ -0,0 +1,52 @@
+/** @internal */
+export function isUri(value: string) {
+  // based on https://github.com/ogt/valid-url
+
+  // check for illegal characters
+  if (/[^a-z0-9\:\/\?\#\[\]\@\!\$\&\'\(\)\*\+\,\;\=\.\-\_\~\%]/i.test(value))
+    return false
+
+  // check for hex escapes that aren't complete
+  if (/%[^0-9a-f]/i.test(value)) return false
+  if (/%[0-9a-f](:?[^0-9a-f]|$)/i.test(value)) return false
+
+  // from RFC 3986
+  const splitted = splitUri(value)
+  const scheme = splitted[1]
+  const authority = splitted[2]
+  const path = splitted[3]
+  const query = splitted[4]
+  const fragment = splitted[5]
+
+  // scheme and path are required, though the path can be empty
+  if (!(scheme?.length && path && path.length >= 0)) return false
+
+  // if authority is present, the path must be empty or begin with a /
+  if (authority?.length) {
+    if (!(path.length === 0 || /^\//.test(path))) return false
+  } else {
+    // if authority is not present, the path must not start with //
+    if (/^\/\//.test(path)) return false
+  }
+
+  // scheme must begin with a letter, then consist of letters, digits, +, ., or -
+  if (!/^[a-z][a-z0-9\+\-\.]*$/.test(scheme.toLowerCase())) return false
+
+  let out = ''
+  // re-assemble the URL per section 5.3 in RFC 3986
+  out += `${scheme}:`
+  if (authority?.length) out += `//${authority}`
+
+  out += path
+
+  if (query?.length) out += `?${query}`
+  if (fragment?.length) out += `#${fragment}`
+
+  return out
+}
+
+function splitUri(value: string) {
+  return value.match(
+    /(?:([^:\/?#]+):)?(?:\/\/([^\/?#]*))?([^?#]*)(?:\?([^#]*))?(?:#(.*))?/,
+  )!
+}
diff --git a/src/internal/siwe/createSiweMessage.test.ts b/src/internal/siwe/createSiweMessage.test.ts
new file mode 100644
index 00000000..f638d7a9
--- /dev/null
+++ b/src/internal/siwe/createSiweMessage.test.ts
@@ -0,0 +1,413 @@
+import { expect, test, vi } from 'vitest'
+
+import type { SiweMessage } from '../types/siwe.js'
+import { createSiweMessage } from './createSiweMessage.js'
+
+const message = {
+  address: '0xA0Cf798816D4b9b9866b5330EEa46a18382f251e',
+  chainId: 1,
+  domain: 'example.com',
+  nonce: 'foobarbaz',
+  uri: 'https://example.com/path',
+  version: '1',
+} satisfies SiweMessage
+
+test('default', () => {
+  vi.useFakeTimers()
+  vi.setSystemTime(new Date(Date.UTC(2023, 1, 1)))
+
+  expect(createSiweMessage(message)).toMatchInlineSnapshot(`
+    "example.com wants you to sign in with your Ethereum account:
+    0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+
+    URI: https://example.com/path
+    Version: 1
+    Chain ID: 1
+    Nonce: foobarbaz
+    Issued At: 2023-02-01T00:00:00.000Z"
+  `)
+
+  vi.useRealTimers()
+})
+
+test('parameters: domain', () => {
+  vi.useFakeTimers()
+  vi.setSystemTime(new Date(Date.UTC(2023, 1, 1)))
+
+  expect(
+    createSiweMessage({
+      ...message,
+      domain: 'foo.example.com',
+    }),
+  ).toMatchInlineSnapshot(`
+    "foo.example.com wants you to sign in with your Ethereum account:
+    0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+
+    URI: https://example.com/path
+    Version: 1
+    Chain ID: 1
+    Nonce: foobarbaz
+    Issued At: 2023-02-01T00:00:00.000Z"
+  `)
+
+  expect(
+    createSiweMessage({
+      ...message,
+      domain: 'example.co.uk',
+    }),
+  ).toMatchInlineSnapshot(`
+    "example.co.uk wants you to sign in with your Ethereum account:
+    0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+
+    URI: https://example.com/path
+    Version: 1
+    Chain ID: 1
+    Nonce: foobarbaz
+    Issued At: 2023-02-01T00:00:00.000Z"
+  `)
+
+  vi.useRealTimers()
+})
+
+test('parameters: scheme', () => {
+  vi.useFakeTimers()
+  vi.setSystemTime(new Date(Date.UTC(2023, 1, 1)))
+
+  expect(
+    createSiweMessage({
+      ...message,
+      scheme: 'https',
+    }),
+  ).toMatchInlineSnapshot(`
+    "https://example.com wants you to sign in with your Ethereum account:
+    0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+
+    URI: https://example.com/path
+    Version: 1
+    Chain ID: 1
+    Nonce: foobarbaz
+    Issued At: 2023-02-01T00:00:00.000Z"
+  `)
+
+  vi.useRealTimers()
+})
+
+test('parameters: statement', () => {
+  vi.useFakeTimers()
+  vi.setSystemTime(new Date(Date.UTC(2023, 1, 1)))
+
+  expect(
+    createSiweMessage({
+      ...message,
+      statement:
+        'I accept the ExampleOrg Terms of Service: https://example.com/tos',
+    }),
+  ).toMatchInlineSnapshot(`
+    "example.com wants you to sign in with your Ethereum account:
+    0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+    I accept the ExampleOrg Terms of Service: https://example.com/tos
+
+    URI: https://example.com/path
+    Version: 1
+    Chain ID: 1
+    Nonce: foobarbaz
+    Issued At: 2023-02-01T00:00:00.000Z"
+  `)
+
+  vi.useRealTimers()
+})
+
+test('parameters: issuedAt', () => {
+  const issuedAt = new Date(Date.UTC(2022, 1, 4))
+  expect(createSiweMessage({ ...message, issuedAt })).toMatchInlineSnapshot(`
+    "example.com wants you to sign in with your Ethereum account:
+    0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+
+    URI: https://example.com/path
+    Version: 1
+    Chain ID: 1
+    Nonce: foobarbaz
+    Issued At: 2022-02-04T00:00:00.000Z"
+  `)
+})
+
+test('parameters: expirationTime', () => {
+  vi.useFakeTimers()
+  vi.setSystemTime(new Date(Date.UTC(2023, 1, 1)))
+
+  expect(
+    createSiweMessage({
+      ...message,
+      expirationTime: new Date(Date.UTC(2022, 1, 4)),
+    }),
+  ).toMatchInlineSnapshot(`
+    "example.com wants you to sign in with your Ethereum account:
+    0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+
+    URI: https://example.com/path
+    Version: 1
+    Chain ID: 1
+    Nonce: foobarbaz
+    Issued At: 2023-02-01T00:00:00.000Z
+    Expiration Time: 2022-02-04T00:00:00.000Z"
+  `)
+
+  vi.useRealTimers()
+})
+
+test('parameters: notBefore', () => {
+  vi.useFakeTimers()
+  vi.setSystemTime(new Date(Date.UTC(2023, 1, 1)))
+
+  expect(
+    createSiweMessage({
+      ...message,
+      notBefore: new Date(Date.UTC(2022, 1, 4)),
+    }),
+  ).toMatchInlineSnapshot(`
+    "example.com wants you to sign in with your Ethereum account:
+    0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+
+    URI: https://example.com/path
+    Version: 1
+    Chain ID: 1
+    Nonce: foobarbaz
+    Issued At: 2023-02-01T00:00:00.000Z
+    Not Before: 2022-02-04T00:00:00.000Z"
+  `)
+
+  vi.useRealTimers()
+})
+
+test('parameters: requestId', () => {
+  vi.useFakeTimers()
+  vi.setSystemTime(new Date(Date.UTC(2023, 1, 1)))
+
+  expect(
+    createSiweMessage({
+      ...message,
+      requestId: '123e4567-e89b-12d3-a456-426614174000',
+    }),
+  ).toMatchInlineSnapshot(`
+    "example.com wants you to sign in with your Ethereum account:
+    0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+
+    URI: https://example.com/path
+    Version: 1
+    Chain ID: 1
+    Nonce: foobarbaz
+    Issued At: 2023-02-01T00:00:00.000Z
+    Request ID: 123e4567-e89b-12d3-a456-426614174000"
+  `)
+
+  vi.useRealTimers()
+})
+
+test('parameters: resources', () => {
+  vi.useFakeTimers()
+  vi.setSystemTime(new Date(Date.UTC(2023, 1, 1)))
+
+  expect(
+    createSiweMessage({
+      ...message,
+      resources: [
+        'https://example.com/foo',
+        'https://example.com/bar',
+        'https://example.com/baz',
+      ],
+    }),
+  ).toMatchInlineSnapshot(`
+    "example.com wants you to sign in with your Ethereum account:
+    0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+
+    URI: https://example.com/path
+    Version: 1
+    Chain ID: 1
+    Nonce: foobarbaz
+    Issued At: 2023-02-01T00:00:00.000Z
+    Resources:
+    - https://example.com/foo
+    - https://example.com/bar
+    - https://example.com/baz"
+  `)
+
+  vi.useRealTimers()
+})
+
+test('behavior: invalid address', () => {
+  expect(() =>
+    createSiweMessage({ ...message, address: '0xfoobarbaz' }),
+  ).toThrowErrorMatchingInlineSnapshot(`
+    [InvalidAddressError: Address "0xfoobarbaz" is invalid.
+
+    Details: Address is not a 20 byte (40 hexadecimal character) value.
+    See: https://oxlib.sh/errors#invalidaddresserror]
+  `)
+})
+
+test('behavior: invalid chainId', () => {
+  expect(() =>
+    createSiweMessage({ ...message, chainId: 1.1 }),
+  ).toThrowErrorMatchingInlineSnapshot(`
+    [SiweInvalidMessageFieldError: Invalid Sign-In with Ethereum message field "chainId".
+
+    - Chain ID must be a EIP-155 chain ID.
+    - See https://eips.ethereum.org/EIPS/eip-155
+
+    Provided value: 1.1
+
+    See: https://oxlib.sh/errors#siweinvalidmessagefielderror]
+  `)
+})
+
+test('behavior: invalid domain', () => {
+  expect(() =>
+    createSiweMessage({ ...message, domain: '#foo' }),
+  ).toThrowErrorMatchingInlineSnapshot(`
+    [SiweInvalidMessageFieldError: Invalid Sign-In with Ethereum message field "domain".
+
+    - Domain must be an RFC 3986 authority.
+    - See https://www.rfc-editor.org/rfc/rfc3986
+
+    Provided value: #foo
+
+    See: https://oxlib.sh/errors#siweinvalidmessagefielderror]
+  `)
+})
+
+test('behavior: invalid nonce', () => {
+  expect(() =>
+    createSiweMessage({ ...message, nonce: '#foo' }),
+  ).toThrowErrorMatchingInlineSnapshot(`
+    [SiweInvalidMessageFieldError: Invalid Sign-In with Ethereum message field "nonce".
+
+    - Nonce must be at least 8 characters.
+    - Nonce must be alphanumeric.
+
+    Provided value: #foo
+
+    See: https://oxlib.sh/errors#siweinvalidmessagefielderror]
+  `)
+})
+
+test('behavior: invalid uri', () => {
+  expect(() =>
+    createSiweMessage({ ...message, uri: '#foo' }),
+  ).toThrowErrorMatchingInlineSnapshot(`
+    [SiweInvalidMessageFieldError: Invalid Sign-In with Ethereum message field "uri".
+
+    - URI must be a RFC 3986 URI referring to the resource that is the subject of the signing.
+    - See https://www.rfc-editor.org/rfc/rfc3986
+
+    Provided value: #foo
+
+    See: https://oxlib.sh/errors#siweinvalidmessagefielderror]
+  `)
+})
+
+test('behavior: invalid version', () => {
+  expect(() =>
+    // @ts-expect-error
+    createSiweMessage({ ...message, version: '2' }),
+  ).toThrowErrorMatchingInlineSnapshot(`
+    [SiweInvalidMessageFieldError: Invalid Sign-In with Ethereum message field "version".
+
+    - Version must be '1'.
+
+    Provided value: 2
+
+    See: https://oxlib.sh/errors#siweinvalidmessagefielderror]
+  `)
+})
+
+test('behavior: invalid scheme', () => {
+  expect(() =>
+    createSiweMessage({ ...message, scheme: 'foo_bar' }),
+  ).toThrowErrorMatchingInlineSnapshot(`
+    [SiweInvalidMessageFieldError: Invalid Sign-In with Ethereum message field "scheme".
+
+    - Scheme must be an RFC 3986 URI scheme.
+    - See https://www.rfc-editor.org/rfc/rfc3986#section-3.1
+
+    Provided value: foo_bar
+
+    See: https://oxlib.sh/errors#siweinvalidmessagefielderror]
+  `)
+})
+
+test('behavior: invalid statement', () => {
+  expect(() =>
+    createSiweMessage({ ...message, statement: 'foo\nbar' }),
+  ).toThrowErrorMatchingInlineSnapshot(`
+    [SiweInvalidMessageFieldError: Invalid Sign-In with Ethereum message field "statement".
+
+    - Statement must not include '\\n'.
+
+    Provided value: foo
+    bar
+
+    See: https://oxlib.sh/errors#siweinvalidmessagefielderror]
+  `)
+})
+
+test('behavior: invalid resources', () => {
+  expect(() =>
+    createSiweMessage({
+      ...message,
+      resources: ['https://example.com', 'foo'],
+    }),
+  ).toThrowErrorMatchingInlineSnapshot(`
+    [SiweInvalidMessageFieldError: Invalid Sign-In with Ethereum message field "resources".
+
+    - Every resource must be a RFC 3986 URI.
+    - See https://www.rfc-editor.org/rfc/rfc3986
+
+    Provided value: https://example.com
+
+    See: https://oxlib.sh/errors#siweinvalidmessagefielderror]
+  `)
+})
+
+test.each([
+  'example.com',
+  'localhost',
+  '127.0.0.1',
+  'example.com:3000',
+  'localhost:3000',
+  '127.0.0.1:3000',
+])('valid domain `%s`', (domain) => {
+  expect(
+    createSiweMessage({
+      ...message,
+      domain,
+    }),
+  ).toBeTypeOf('string')
+})
+
+test.each([
+  'http://example.com',
+  'http://localhost',
+  'http://127.0.0.1',
+  'http://example.com:3000',
+  'http://localhost:3000',
+  'http://127.0.0.1:3000',
+  'foobarbaz',
+  '-example.com',
+])('invalid domain `%s`', (domain) => {
+  expect(() =>
+    createSiweMessage({
+      ...message,
+      domain,
+    }),
+  ).toThrowError()
+})
diff --git a/src/internal/siwe/createSiweMessage.ts b/src/internal/siwe/createSiweMessage.ts
new file mode 100644
index 00000000..98b2ceb9
--- /dev/null
+++ b/src/internal/siwe/createSiweMessage.ts
@@ -0,0 +1,192 @@
+import type { GlobalErrorType } from 'src/Errors.js'
+import { toAddress } from '../address/from.js'
+import { SiweInvalidMessageFieldError } from '../errors/siwe.js'
+import { isUri } from '../isUri.js'
+import type { SiweMessage } from '../types/siwe.js'
+
+/**
+ * Creates EIP-4361 formatted message.
+ *
+ * - Docs: https://oxlib.sh/api/siwe/createMessage
+ * - Spec: https://eips.ethereum.org/EIPS/eip-4361
+ *
+ * @example
+ * import { Siwe } from 'ox'
+ *
+ * Siwe.createMessage({
+ *   address: '0xA0Cf798816D4b9b9866b5330EEa46a18382f251e',
+ *   chainId: 1,
+ *   domain: 'example.com',
+ *   nonce: 'foobarbaz',
+ *   uri: 'https://example.com/path',
+ *   version: '1',
+ * })
+ * // "example.com wants you to sign in with your Ethereum account:
+ * // 0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+ * //
+ * //
+ * // URI: https://example.com/path
+ * // Version: 1
+ * // Chain ID: 1
+ * // Nonce: foobarbaz
+ * // Issued At: 2023-02-01T00:00:00.000Z"
+ */
+export function createSiweMessage(
+  value: createSiweMessage.Value,
+): createSiweMessage.ReturnType {
+  const {
+    chainId,
+    domain,
+    expirationTime,
+    issuedAt = new Date(),
+    nonce,
+    notBefore,
+    requestId,
+    resources,
+    scheme,
+    uri,
+    version,
+  } = value
+
+  // Validate fields
+  {
+    // Required fields
+    if (chainId !== Math.floor(chainId))
+      throw new SiweInvalidMessageFieldError({
+        field: 'chainId',
+        metaMessages: [
+          '- Chain ID must be a EIP-155 chain ID.',
+          '- See https://eips.ethereum.org/EIPS/eip-155',
+          '',
+          `Provided value: ${chainId}`,
+        ],
+      })
+    if (
+      !(
+        domainRegex.test(domain) ||
+        ipRegex.test(domain) ||
+        localhostRegex.test(domain)
+      )
+    )
+      throw new SiweInvalidMessageFieldError({
+        field: 'domain',
+        metaMessages: [
+          '- Domain must be an RFC 3986 authority.',
+          '- See https://www.rfc-editor.org/rfc/rfc3986',
+          '',
+          `Provided value: ${domain}`,
+        ],
+      })
+    if (!nonceRegex.test(nonce))
+      throw new SiweInvalidMessageFieldError({
+        field: 'nonce',
+        metaMessages: [
+          '- Nonce must be at least 8 characters.',
+          '- Nonce must be alphanumeric.',
+          '',
+          `Provided value: ${nonce}`,
+        ],
+      })
+    if (!isUri(uri))
+      throw new SiweInvalidMessageFieldError({
+        field: 'uri',
+        metaMessages: [
+          '- URI must be a RFC 3986 URI referring to the resource that is the subject of the signing.',
+          '- See https://www.rfc-editor.org/rfc/rfc3986',
+          '',
+          `Provided value: ${uri}`,
+        ],
+      })
+    if (version !== '1')
+      throw new SiweInvalidMessageFieldError({
+        field: 'version',
+        metaMessages: [
+          "- Version must be '1'.",
+          '',
+          `Provided value: ${version}`,
+        ],
+      })
+
+    // Optional fields
+    if (scheme && !schemeRegex.test(scheme))
+      throw new SiweInvalidMessageFieldError({
+        field: 'scheme',
+        metaMessages: [
+          '- Scheme must be an RFC 3986 URI scheme.',
+          '- See https://www.rfc-editor.org/rfc/rfc3986#section-3.1',
+          '',
+          `Provided value: ${scheme}`,
+        ],
+      })
+    const statement = value.statement
+    if (statement?.includes('\n'))
+      throw new SiweInvalidMessageFieldError({
+        field: 'statement',
+        metaMessages: [
+          "- Statement must not include '\\n'.",
+          '',
+          `Provided value: ${statement}`,
+        ],
+      })
+  }
+
+  // Construct message
+  const address = toAddress(value.address)
+  const origin = (() => {
+    if (scheme) return `${scheme}://${domain}`
+    return domain
+  })()
+  const statement = (() => {
+    if (!value.statement) return ''
+    return `${value.statement}\n`
+  })()
+  const prefix = `${origin} wants you to sign in with your Ethereum account:\n${address}\n\n${statement}`
+
+  let suffix = `URI: ${uri}\nVersion: ${version}\nChain ID: ${chainId}\nNonce: ${nonce}\nIssued At: ${issuedAt.toISOString()}`
+
+  if (expirationTime)
+    suffix += `\nExpiration Time: ${expirationTime.toISOString()}`
+  if (notBefore) suffix += `\nNot Before: ${notBefore.toISOString()}`
+  if (requestId) suffix += `\nRequest ID: ${requestId}`
+  if (resources) {
+    let content = '\nResources:'
+    for (const resource of resources) {
+      if (!isUri(resource))
+        throw new SiweInvalidMessageFieldError({
+          field: 'resources',
+          metaMessages: [
+            '- Every resource must be a RFC 3986 URI.',
+            '- See https://www.rfc-editor.org/rfc/rfc3986',
+            '',
+            `Provided value: ${resource}`,
+          ],
+        })
+      content += `\n- ${resource}`
+    }
+    suffix += content
+  }
+
+  return `${prefix}\n${suffix}`
+}
+
+export declare namespace createSiweMessage {
+  type Value = SiweMessage
+
+  type ReturnType = string
+
+  type ErrorType =
+    | toAddress.ErrorType
+    | SiweInvalidMessageFieldError
+    | GlobalErrorType
+}
+
+createSiweMessage.parseError = (error: unknown) =>
+  error as createSiweMessage.ErrorType
+
+const domainRegex =
+  /^([a-zA-Z0-9]([a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?\.)+[a-zA-Z]{2,}(:[0-9]{1,5})?$/
+const ipRegex =
+  /^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(:[0-9]{1,5})?$/
+const localhostRegex = /^localhost(:[0-9]{1,5})?$/
+const nonceRegex = /^[a-zA-Z0-9]{8,}$/
+const schemeRegex = /^([a-zA-Z][a-zA-Z0-9+-.]*)$/
diff --git a/src/internal/siwe/generateSiweNonce.test.ts b/src/internal/siwe/generateSiweNonce.test.ts
new file mode 100644
index 00000000..3072065a
--- /dev/null
+++ b/src/internal/siwe/generateSiweNonce.test.ts
@@ -0,0 +1,8 @@
+import { expect, test } from 'vitest'
+
+import { generateSiweNonce } from './generateSiweNonce.js'
+
+test('default', () => {
+  const nonce = generateSiweNonce()
+  expect(nonce.length).toMatchInlineSnapshot('96')
+})
diff --git a/src/internal/siwe/generateSiweNonce.ts b/src/internal/siwe/generateSiweNonce.ts
new file mode 100644
index 00000000..c51f43fc
--- /dev/null
+++ b/src/internal/siwe/generateSiweNonce.ts
@@ -0,0 +1,17 @@
+import { uid } from '../uid.js'
+
+/**
+ * Generates random EIP-4361 nonce.
+ *
+ * - Docs: https://oxlib.sh/api/siwe/generateNonce
+ * - Spec: https://eips.ethereum.org/EIPS/eip-4361
+ *
+ * @example
+ * import { Siwe } from 'ox'
+ *
+ * Siwe.generateNonce()
+ * // '65ed4681d4efe0270b923ff5f4b097b1c95974dc33aeebecd5724c42fd86dfd25dc70b27ef836b2aa22e68f19ebcccc1'
+ */
+export function generateSiweNonce(): string {
+  return uid(96)
+}
diff --git a/src/internal/siwe/parseSiweMessage.test.ts b/src/internal/siwe/parseSiweMessage.test.ts
new file mode 100644
index 00000000..28192c02
--- /dev/null
+++ b/src/internal/siwe/parseSiweMessage.test.ts
@@ -0,0 +1,182 @@
+import { expect, test } from 'vitest'
+
+import { parseSiweMessage } from './parseSiweMessage.js'
+
+test('default', () => {
+  const message = `example.com wants you to sign in with your Ethereum account:
+0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+I accept the ExampleOrg Terms of Service: https://example.com/tos
+
+URI: https://example.com/path
+Version: 1
+Chain ID: 1
+Nonce: foobarbaz
+Issued At: 2023-02-01T00:00:00.000Z`
+  const parsed = parseSiweMessage(message)
+  expect(parsed).toMatchInlineSnapshot(`
+    {
+      "address": "0xA0Cf798816D4b9b9866b5330EEa46a18382f251e",
+      "chainId": 1,
+      "domain": "example.com",
+      "issuedAt": 2023-02-01T00:00:00.000Z,
+      "nonce": "foobarbaz",
+      "statement": "I accept the ExampleOrg Terms of Service: https://example.com/tos",
+      "uri": "https://example.com/path",
+      "version": "1",
+    }
+  `)
+})
+
+test('behavior: with scheme', () => {
+  const message = `https://example.com wants you to sign in with your Ethereum account:
+0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+URI: https://example.com/path
+Version: 1
+Chain ID: 1
+Nonce: foobarbaz
+Issued At: 2023-02-01T00:00:00.000Z`
+  const parsed = parseSiweMessage(message)
+  expect(parsed.scheme).toMatchInlineSnapshot(`"https"`)
+})
+
+test('behavior: domain with port', () => {
+  const message = `example.com:8080 wants you to sign in with your Ethereum account:
+0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+URI: https://example.com/path
+Version: 1
+Chain ID: 1
+Nonce: foobarbaz
+Issued At: 2023-02-01T00:00:00.000Z`
+  const parsed = parseSiweMessage(message)
+  expect(parsed.domain).toMatchInlineSnapshot(`"example.com:8080"`)
+})
+
+test('behavior: with statement', () => {
+  const message = `example.com wants you to sign in with your Ethereum account:
+0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+I accept the ExampleOrg Terms of Service: https://example.com/tos
+
+URI: https://example.com/path
+Version: 1
+Chain ID: 1
+Nonce: foobarbaz
+Issued At: 2023-02-01T00:00:00.000Z`
+  const parsed = parseSiweMessage(message)
+  expect(parsed.statement).toMatchInlineSnapshot(
+    `"I accept the ExampleOrg Terms of Service: https://example.com/tos"`,
+  )
+})
+
+test('behavior: with expirationTime', () => {
+  const message = `https://example.com wants you to sign in with your Ethereum account:
+0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+URI: https://example.com/path
+Version: 1
+Chain ID: 1
+Nonce: foobarbaz
+Issued At: 2023-02-01T00:00:00.000Z
+Expiration Time: 2022-02-04T00:00:00.000Z`
+  const parsed = parseSiweMessage(message)
+  expect(parsed.expirationTime).toMatchInlineSnapshot(
+    '2022-02-04T00:00:00.000Z',
+  )
+})
+
+test('behavior: with notBefore', () => {
+  const message = `https://example.com wants you to sign in with your Ethereum account:
+0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+URI: https://example.com/path
+Version: 1
+Chain ID: 1
+Nonce: foobarbaz
+Issued At: 2023-02-01T00:00:00.000Z
+Not Before: 2022-02-04T00:00:00.000Z`
+  const parsed = parseSiweMessage(message)
+  expect(parsed.notBefore).toMatchInlineSnapshot('2022-02-04T00:00:00.000Z')
+})
+
+test('behavior: with requestId', () => {
+  const message = `https://example.com wants you to sign in with your Ethereum account:
+0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+URI: https://example.com/path
+Version: 1
+Chain ID: 1
+Nonce: foobarbaz
+Issued At: 2023-02-01T00:00:00.000Z
+Request ID: 123e4567-e89b-12d3-a456-426614174000`
+  const parsed = parseSiweMessage(message)
+  expect(parsed.requestId).toMatchInlineSnapshot(
+    `"123e4567-e89b-12d3-a456-426614174000"`,
+  )
+})
+
+test('behavior: with resources', () => {
+  const message = `https://example.com wants you to sign in with your Ethereum account:
+0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+URI: https://example.com/path
+Version: 1
+Chain ID: 1
+Nonce: foobarbaz
+Issued At: 2023-02-01T00:00:00.000Z
+Resources:
+- https://example.com/foo
+- https://example.com/bar
+- https://example.com/baz`
+  const parsed = parseSiweMessage(message)
+  expect(parsed.resources).toMatchInlineSnapshot(`
+    [
+      "https://example.com/foo",
+      "https://example.com/bar",
+      "https://example.com/baz",
+    ]
+  `)
+})
+
+test('behavior: no suffix', () => {
+  const message = `https://example.com wants you to sign in with your Ethereum account:
+0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+
+`
+  const parsed = parseSiweMessage(message)
+  expect(parsed).toMatchInlineSnapshot(`
+    {
+      "address": "0xA0Cf798816D4b9b9866b5330EEa46a18382f251e",
+      "domain": "example.com",
+      "scheme": "https",
+    }
+  `)
+})
+
+test('behavior: no prefix', () => {
+  const message = `URI: https://example.com/path
+Version: 1
+Chain ID: 1
+Nonce: foobarbaz
+Issued At: 2023-02-01T00:00:00.000Z
+Request ID: 123e4567-e89b-12d3-a456-426614174000`
+  const parsed = parseSiweMessage(message)
+  expect(parsed).toMatchInlineSnapshot(`
+    {
+      "chainId": 1,
+      "issuedAt": 2023-02-01T00:00:00.000Z,
+      "nonce": "foobarbaz",
+      "requestId": "123e4567-e89b-12d3-a456-426614174000",
+      "uri": "https://example.com/path",
+      "version": "1",
+    }
+  `)
+})
+
+test('behavior: bogus message', () => {
+  const message = 'foobarbaz'
+  const parsed = parseSiweMessage(message)
+  expect(parsed).toMatchInlineSnapshot('{}')
+})
diff --git a/src/internal/siwe/parseSiweMessage.ts b/src/internal/siwe/parseSiweMessage.ts
new file mode 100644
index 00000000..dcb1c55f
--- /dev/null
+++ b/src/internal/siwe/parseSiweMessage.ts
@@ -0,0 +1,79 @@
+import type { Address } from 'abitype'
+import type { SiweMessage } from '../types/siwe.js'
+import type { Compute, ExactPartial } from '../types/utils.js'
+
+/**
+ * EIP-4361 formatted message into message fields object.
+ *
+ * - Docs: https://oxlib.sh/api/siwe/parseMessage
+ * - Spec: https://eips.ethereum.org/EIPS/eip-4361
+ *
+ * @example
+ * import { Siwe } from 'ox'
+ *
+ * Siwe.parseMessage(`example.com wants you to sign in with your Ethereum account:
+ * 0xA0Cf798816D4b9b9866b5330EEa46a18382f251e
+ *
+ * I accept the ExampleOrg Terms of Service: https://example.com/tos
+ *
+ * URI: https://example.com/path
+ * Version: 1
+ * Chain ID: 1
+ * Nonce: foobarbaz
+ * Issued At: 2023-02-01T00:00:00.000Z`)
+ * // {
+ * //   address: '0xA0Cf798816D4b9b9866b5330EEa46a18382f251e',
+ * //   chainId: 1,
+ * //   domain: 'example.com',
+ * //   issuedAt: '2023-02-01T00:00:00.000Z',
+ * //   nonce: 'foobarbaz',
+ * //   statement: 'I accept the ExampleOrg Terms of Service: https://example.com/tos',
+ * //   uri: 'https://example.com/path',
+ * //   version: '1',
+ * // }
+ */
+export function parseSiweMessage(message: string): parseSiweMessage.ReturnType {
+  const { scheme, statement, ...prefix } = (message.match(prefixRegex)
+    ?.groups ?? {}) as {
+    address: Address
+    domain: string
+    scheme?: string
+    statement?: string
+  }
+  const { chainId, expirationTime, issuedAt, notBefore, requestId, ...suffix } =
+    (message.match(suffixRegex)?.groups ?? {}) as {
+      chainId: string
+      expirationTime?: string
+      issuedAt?: string
+      nonce: string
+      notBefore?: string
+      requestId?: string
+      uri: string
+      version: '1'
+    }
+  const resources = message.split('Resources:')[1]?.split('\n- ').slice(1)
+  return {
+    ...prefix,
+    ...suffix,
+    ...(chainId ? { chainId: Number(chainId) } : {}),
+    ...(expirationTime ? { expirationTime: new Date(expirationTime) } : {}),
+    ...(issuedAt ? { issuedAt: new Date(issuedAt) } : {}),
+    ...(notBefore ? { notBefore: new Date(notBefore) } : {}),
+    ...(requestId ? { requestId } : {}),
+    ...(resources ? { resources } : {}),
+    ...(scheme ? { scheme } : {}),
+    ...(statement ? { statement } : {}),
+  }
+}
+
+export declare namespace parseSiweMessage {
+  type ReturnType = Compute<ExactPartial<SiweMessage>>
+}
+
+// https://regexr.com/80gdj
+const prefixRegex =
+  /^(?:(?<scheme>[a-zA-Z][a-zA-Z0-9+-.]*):\/\/)?(?<domain>[a-zA-Z0-9+-.]*(?::[0-9]{1,5})?) (?:wants you to sign in with your Ethereum account:\n)(?<address>0x[a-fA-F0-9]{40})\n\n(?:(?<statement>.*)\n\n)?/
+
+// https://regexr.com/80gf9
+const suffixRegex =
+  /(?:URI: (?<uri>.+))\n(?:Version: (?<version>.+))\n(?:Chain ID: (?<chainId>\d+))\n(?:Nonce: (?<nonce>[a-zA-Z0-9]+))\n(?:Issued At: (?<issuedAt>.+))(?:\nExpiration Time: (?<expirationTime>.+))?(?:\nNot Before: (?<notBefore>.+))?(?:\nRequest ID: (?<requestId>.+))?/
diff --git a/src/internal/siwe/validateSiweMessage.test.ts b/src/internal/siwe/validateSiweMessage.test.ts
new file mode 100644
index 00000000..5f792217
--- /dev/null
+++ b/src/internal/siwe/validateSiweMessage.test.ts
@@ -0,0 +1,109 @@
+import { expect, test, vi } from 'vitest'
+
+import type { SiweMessage } from '../types/siwe.js'
+import { validateSiweMessage } from './validateSiweMessage.js'
+
+const message = {
+  address: '0xA0Cf798816D4b9b9866b5330EEa46a18382f251e',
+  chainId: 1,
+  domain: 'example.com',
+  nonce: 'foobarbaz',
+  uri: 'https://example.com/path',
+  version: '1',
+} satisfies SiweMessage
+
+test('default', () => {
+  expect(
+    validateSiweMessage({
+      message,
+    }),
+  ).toBeTruthy()
+})
+
+test('behavior: invalid address', () => {
+  expect(
+    validateSiweMessage({
+      message: {
+        ...message,
+        address: undefined,
+      },
+    }),
+  ).toBeFalsy()
+})
+
+test('behavior: address mismatch', () => {
+  expect(
+    validateSiweMessage({
+      address: '0xd2135CfB216b74109775236E36d4b433F1DF507B',
+      message,
+    }),
+  ).toBeFalsy()
+})
+
+test('behavior: invalid address', () => {
+  expect(
+    validateSiweMessage({
+      address: '0xfoobarbaz',
+      message,
+    }),
+  ).toBeFalsy()
+})
+
+test('behavior: domain mismatch', () => {
+  expect(
+    validateSiweMessage({
+      domain: 'viem.sh',
+      message,
+    }),
+  ).toBeFalsy()
+})
+
+test('behavior: nonce mismatch', () => {
+  expect(
+    validateSiweMessage({
+      nonce: 'f0obarbaz',
+      message,
+    }),
+  ).toBeFalsy()
+})
+
+test('behavior: scheme mismatch', () => {
+  expect(
+    validateSiweMessage({
+      scheme: 'http',
+      message: {
+        ...message,
+        scheme: 'https',
+      },
+    }),
+  ).toBeFalsy()
+})
+
+test('behavior: time is after expirationTime', () => {
+  expect(
+    validateSiweMessage({
+      message: {
+        ...message,
+        expirationTime: new Date(Date.UTC(2024, 1, 1)),
+      },
+      time: new Date(Date.UTC(2025, 1, 1)),
+    }),
+  ).toBeFalsy()
+})
+
+test('behavior: time is before notBefore', () => {
+  vi.useFakeTimers()
+  vi.setSystemTime(new Date(Date.UTC(2023, 1, 1)))
+
+  expect(
+    validateSiweMessage({
+      message: {
+        ...message,
+        notBefore: new Date(Date.UTC(2024, 1, 1)),
+      },
+      time: new Date(Date.UTC(2023, 1, 1)),
+    }),
+  ).toBeFalsy()
+
+  vi.useRealTimers()
+})
diff --git a/src/internal/siwe/validateSiweMessage.ts b/src/internal/siwe/validateSiweMessage.ts
new file mode 100644
index 00000000..a2103ab4
--- /dev/null
+++ b/src/internal/siwe/validateSiweMessage.ts
@@ -0,0 +1,79 @@
+import type { Address } from 'abitype'
+
+import { isAddressEqual } from '../address/isEqual.js'
+import type { SiweMessage } from '../types/siwe.js'
+import type { ExactPartial } from '../types/utils.js'
+
+/**
+ * Validates EIP-4361 message.
+ *
+ * - Docs: https://oxlib.sh/api/siwe/validateMessage
+ * - Spec: https://eips.ethereum.org/EIPS/eip-4361
+ *
+ * @example
+ * import { Siwe } from 'ox'
+ *
+ * Siwe.validateMessage({
+ *   address: '0xA0Cf798816D4b9b9866b5330EEa46a18382f251e',
+ *   chainId: 1,
+ *   domain: 'example.com',
+ *   nonce: 'foobarbaz',
+ *   uri: 'https://example.com/path',
+ *   version: '1',
+ * })
+ * // true
+ */
+export function validateSiweMessage(
+  value: validateSiweMessage.Value,
+): validateSiweMessage.ReturnType {
+  const { address, domain, message, nonce, scheme, time = new Date() } = value
+
+  if (domain && message.domain !== domain) return false
+  if (nonce && message.nonce !== nonce) return false
+  if (scheme && message.scheme !== scheme) return false
+
+  if (message.expirationTime && time >= message.expirationTime) return false
+  if (message.notBefore && time < message.notBefore) return false
+
+  try {
+    if (!message.address) return false
+    if (address && !isAddressEqual(message.address, address)) return false
+  } catch {
+    return false
+  }
+
+  return true
+}
+
+export declare namespace validateSiweMessage {
+  type Value = {
+    /**
+     * Ethereum address to check against.
+     */
+    address?: Address | undefined
+    /**
+     * [RFC 3986](https://www.rfc-editor.org/rfc/rfc3986) authority to check against.
+     */
+    domain?: string | undefined
+    /**
+     * EIP-4361 message fields.
+     */
+    message: ExactPartial<SiweMessage>
+    /**
+     * Random string to check against.
+     */
+    nonce?: string | undefined
+    /**
+     * [RFC 3986](https://www.rfc-editor.org/rfc/rfc3986#section-3.1) URI scheme to check against.
+     */
+    scheme?: string | undefined
+    /**
+     * Current time to check optional `expirationTime` and `notBefore` fields.
+     *
+     * @default new Date()
+     */
+    time?: Date | undefined
+  }
+
+  type ReturnType = boolean
+}
diff --git a/src/internal/typedData/domainSeparator.ts b/src/internal/typedData/domainSeparator.ts
index 781fdf7d..b08494e5 100644
--- a/src/internal/typedData/domainSeparator.ts
+++ b/src/internal/typedData/domainSeparator.ts
@@ -9,6 +9,7 @@ import { hashDomain } from './hashDomain.js'
  * Creates [EIP-712 Typed Data](https://eips.ethereum.org/EIPS/eip-712) domainSeparator for the provided domain.
  *
  * - Docs: https://oxlib.sh/api/typedData/domainSeparator
+ * - Spec: https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator
  *
  * @example
  * import { TypedData } from 'ox'
diff --git a/src/internal/typedData/encodeType.ts b/src/internal/typedData/encodeType.ts
index 80e44127..5d84a1a1 100644
--- a/src/internal/typedData/encodeType.ts
+++ b/src/internal/typedData/encodeType.ts
@@ -7,6 +7,7 @@ import type { GlobalErrorType } from '../errors/error.js'
  * Encodes [EIP-712 Typed Data](https://eips.ethereum.org/EIPS/eip-712) schema for the provided primaryType.
  *
  * - Docs: https://oxlib.sh/api/typedData/encodeType
+ * - Spec: https://eips.ethereum.org/EIPS/eip-712#definition-of-encodetype
  *
  * @example
  * import { TypedData } from 'ox'
diff --git a/src/internal/typedData/hashStruct.ts b/src/internal/typedData/hashStruct.ts
index 6fff0895..7b8873a1 100644
--- a/src/internal/typedData/hashStruct.ts
+++ b/src/internal/typedData/hashStruct.ts
@@ -14,6 +14,7 @@ import { encodeType } from './encodeType.js'
  * Hashes [EIP-712 Typed Data](https://eips.ethereum.org/EIPS/eip-712) struct.
  *
  * - Docs: https://oxlib.sh/api/typedData/hashStruct
+ * - Spec: https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct
  *
  * @example
  * import { TypedData } from 'ox'
diff --git a/src/internal/types/siwe.ts b/src/internal/types/siwe.ts
new file mode 100644
index 00000000..11427446
--- /dev/null
+++ b/src/internal/types/siwe.ts
@@ -0,0 +1,61 @@
+import type { Address } from 'abitype'
+
+/**
+ * EIP-4361 message fields
+ *
+ * @see https://eips.ethereum.org/EIPS/eip-4361
+ */
+export type SiweMessage = {
+  /**
+   * The Ethereum address performing the signing.
+   */
+  address: Address
+  /**
+   * The [EIP-155](https://eips.ethereum.org/EIPS/eip-155) Chain ID to which the session is bound,
+   */
+  chainId: number
+  /**
+   * [RFC 3986](https://www.rfc-editor.org/rfc/rfc3986) authority that is requesting the signing.
+   */
+  domain: string
+  /**
+   * Time when the signed authentication message is no longer valid.
+   */
+  expirationTime?: Date | undefined
+  /**
+   * Time when the message was generated, typically the current time.
+   */
+  issuedAt?: Date | undefined
+  /**
+   * A random string typically chosen by the relying party and used to prevent replay attacks.
+   */
+  nonce: string
+  /**
+   * Time when the signed authentication message will become valid.
+   */
+  notBefore?: Date | undefined
+  /**
+   * A system-specific identifier that may be used to uniquely refer to the sign-in request.
+   */
+  requestId?: string | undefined
+  /**
+   * A list of information or references to information the user wishes to have resolved as part of authentication by the relying party.
+   */
+  resources?: string[] | undefined
+  /**
+   * [RFC 3986](https://www.rfc-editor.org/rfc/rfc3986#section-3.1) URI scheme of the origin of the request.
+   */
+  scheme?: string | undefined
+  /**
+   * A human-readable ASCII assertion that the user will sign.
+   */
+  statement?: string | undefined
+  /**
+   * [RFC 3986](https://www.rfc-editor.org/rfc/rfc3986) URI referring to the resource that is the subject of the signing (as in the subject of a claim).
+   */
+  uri: string
+  /**
+   * The current version of the SIWE Message.
+   */
+  version: '1'
+}
diff --git a/src/internal/uid.test.ts b/src/internal/uid.test.ts
new file mode 100644
index 00000000..37c03a6d
--- /dev/null
+++ b/src/internal/uid.test.ts
@@ -0,0 +1,7 @@
+import { expect, test } from 'vitest'
+
+import { uid } from './uid.js'
+
+test('default', () => {
+  expect(uid()).toBeTypeOf('string')
+})
diff --git a/src/internal/uid.ts b/src/internal/uid.ts
new file mode 100644
index 00000000..1744b166
--- /dev/null
+++ b/src/internal/uid.ts
@@ -0,0 +1,15 @@
+const size = 256
+let index = size
+let buffer: string
+
+/** @internal */
+export function uid(length = 11) {
+  if (!buffer || index + length > size * 2) {
+    buffer = ''
+    index = 0
+    for (let i = 0; i < size; i++) {
+      buffer += ((256 + Math.random() * 256) | 0).toString(16).substring(1)
+    }
+  }
+  return buffer.substring(index, index++ + length)
+}