diff --git a/packages/toolkit/core-kit/src/index.ts b/packages/toolkit/core-kit/src/index.ts
index cc5986117..57cea93ca 100644
--- a/packages/toolkit/core-kit/src/index.ts
+++ b/packages/toolkit/core-kit/src/index.ts
@@ -3,3 +3,4 @@ export * from './regex.js';
 export * from './scope.js';
 export * from './models/index.js';
 export * from './http.js';
+export * from './password-policy.js';
diff --git a/packages/toolkit/core-kit/src/password-policy.test.ts b/packages/toolkit/core-kit/src/password-policy.test.ts
new file mode 100644
index 000000000..4dc85e1f0
--- /dev/null
+++ b/packages/toolkit/core-kit/src/password-policy.test.ts
@@ -0,0 +1,195 @@
+import { ZodError } from 'zod';
+
+import { PasswordPolicyChecker } from './password-policy.js';
+
+const { jest } = import.meta;
+
+const mockPwnResponse = () => {
+  const originalFetch = global.fetch;
+  beforeAll(() => {
+    // eslint-disable-next-line @silverhand/fp/no-mutation
+    global.fetch = jest.fn().mockResolvedValue({
+      // Return hash suffixes for '123456'.
+      text: async () =>
+        'D032E84B0AEB4E773555C73D6B13BEA7A44:1\nD09CA3762AF61E59520943DC26494F8941B:37615252',
+    });
+  });
+
+  afterAll(() => {
+    // eslint-disable-next-line @silverhand/fp/no-mutation
+    global.fetch = originalFetch;
+  });
+};
+
+describe('PasswordPolicyChecker', () => {
+  it('should reject malformed policy', () => {
+    expect(() => {
+      // @ts-expect-error
+      return new PasswordPolicyChecker({ length: { min: 1, max: 2 } });
+    }).toThrowError(ZodError);
+  });
+});
+
+describe('PasswordPolicyChecker -> check()', () => {
+  mockPwnResponse();
+
+  const checker = new PasswordPolicyChecker({
+    length: { min: 7, max: 8 },
+    characterTypes: { min: 2 },
+    rejects: {
+      pwned: true,
+      repetitionAndSequence: true,
+      words: [{ type: 'custom', value: 'test' }],
+    },
+  });
+
+  it('should accept valid password', async () => {
+    expect(await checker.check('aL1!aL1!')).toEqual([]);
+  });
+
+  it('should reject with all failed checks', async () => {
+    expect(await checker.check('aaa')).toEqual([
+      { code: 'password_rejected.too_short' },
+      { code: 'password_rejected.character_types', interpolation: { min: 2 } },
+      { code: 'password_rejected.repetition' },
+    ]);
+
+    expect(await checker.check('123456')).toEqual([
+      { code: 'password_rejected.too_short' },
+      { code: 'password_rejected.character_types', interpolation: { min: 2 } },
+      { code: 'password_rejected.pwned' },
+      { code: 'password_rejected.sequence' },
+    ]);
+
+    expect(await checker.check('aaaaaatest😀')).toEqual([
+      { code: 'password_rejected.too_long' },
+      { code: 'password_rejected.unsupported_characters' },
+      { code: 'password_rejected.repetition' },
+      {
+        code: 'password_rejected.restricted_words',
+        interpolation: { type: 'custom', value: 'test' },
+      },
+    ]);
+  });
+});
+
+describe('PasswordPolicyChecker -> checkCharTypes()', () => {
+  const checker1 = new PasswordPolicyChecker({
+    length: { min: 1, max: 256 },
+    characterTypes: { min: 2 },
+    rejects: { pwned: false, repetitionAndSequence: false, words: [] },
+  });
+  const checker2 = new PasswordPolicyChecker({
+    length: { min: 1, max: 256 },
+    characterTypes: { min: 4 },
+    rejects: { pwned: false, repetitionAndSequence: false, words: [] },
+  });
+
+  it('should reject unsupported characters', () => {
+    expect(checker1.checkCharTypes('😀')).toBe('unsupported');
+    expect(checker2.checkCharTypes('aA1!😀')).toBe('unsupported');
+  });
+
+  it('should reject password with too few character types', () => {
+    expect(checker1.checkCharTypes('a')).toBe(false);
+    expect(checker2.checkCharTypes('aA')).toBe(false);
+  });
+
+  it('should accept password with enough character types', () => {
+    expect(checker1.checkCharTypes('aA')).toBe(true);
+    expect(checker1.checkCharTypes('aA1!0')).toBe(true);
+    expect(checker2.checkCharTypes('aA1!0')).toBe(true);
+  });
+});
+
+describe('PasswordPolicyChecker -> hasBeenPwned()', () => {
+  const checker = new PasswordPolicyChecker({
+    length: { min: 1, max: 256 },
+    characterTypes: { min: 2 },
+    rejects: { pwned: true, repetitionAndSequence: false, words: [] },
+  });
+
+  mockPwnResponse();
+
+  it('should reject pwned password', async () => {
+    expect(await checker.hasBeenPwned('123456')).toBe(true);
+  });
+
+  it('should accept non-pwned password', async () => {
+    expect(await checker.hasBeenPwned('1')).toBe(false);
+  });
+});
+
+describe('PasswordPolicyChecker -> hasRepetition()', () => {
+  const checker = new PasswordPolicyChecker({
+    length: { min: 1, max: 256 },
+    characterTypes: { min: 2 },
+    rejects: { pwned: false, repetitionAndSequence: true, words: [] },
+  });
+
+  it('should reject password with too many repeated characters', () => {
+    expect(checker.hasRepetition('aaaa')).toBe(true);
+    expect(checker.hasRepetition('aL1!bbbbb')).toBe(true);
+    expect(checker.hasRepetition('aaaaaatest😀')).toBe(true);
+  });
+
+  it('should accept password with few repeated characters', () => {
+    expect(checker.hasRepetition('aL1!')).toBe(false);
+    expect(checker.hasRepetition('aL1!bbbb')).toBe(false);
+  });
+});
+
+describe('PasswordPolicyChecker -> hasWords()', () => {
+  const checker = new PasswordPolicyChecker({
+    length: { min: 1, max: 256 },
+    characterTypes: { min: 2 },
+    rejects: {
+      pwned: false,
+      repetitionAndSequence: false,
+      words: [
+        { type: 'custom', value: 'test' },
+        { type: 'custom', value: 'teSt2' },
+        { type: 'personal', value: 'TesT3' },
+      ],
+    },
+  });
+
+  it('should reject password with blacklisted words (case insensitive)', () => {
+    expect(checker.hasWords('test')).toEqual([{ type: 'custom', value: 'test' }]);
+    expect(checker.hasWords('tEst2')).toEqual([
+      { type: 'custom', value: 'test' },
+      { type: 'custom', value: 'test2' },
+    ]);
+    expect(checker.hasWords('tEST TEst2 teSt3')).toEqual([
+      { type: 'custom', value: 'test' },
+      { type: 'custom', value: 'test2' },
+      { type: 'personal', value: 'test3' },
+    ]);
+  });
+
+  it('should accept password without blacklisted words', () => {
+    expect(checker.hasWords('tes4')).toEqual([]);
+    expect(checker.hasWords('tes4 est5 tes t')).toEqual([]);
+  });
+});
+
+describe('PasswordPolicyChecker -> hasSequentialChars()', () => {
+  const checker = new PasswordPolicyChecker({
+    length: { min: 1, max: 256 },
+    characterTypes: { min: 2 },
+    rejects: { pwned: false, repetitionAndSequence: true, words: [] },
+  });
+
+  it('should reject password with too many sequential characters', () => {
+    expect(checker.hasSequentialChars('FE')).toBe(true);
+    expect(checker.hasSequentialChars('1234')).toBe(true);
+    expect(checker.hasSequentialChars('edcba')).toBe(true);
+    expect(checker.hasSequentialChars('aL1!BCDEFA')).toBe(true);
+  });
+
+  it('should accept password with few sequential characters', () => {
+    expect(checker.hasSequentialChars('z')).toBe(false);
+    expect(checker.hasSequentialChars('aL1!')).toBe(false);
+    expect(checker.hasSequentialChars('aL1!bcdedcb1234321')).toBe(false);
+  });
+});
diff --git a/packages/toolkit/core-kit/src/password-policy.ts b/packages/toolkit/core-kit/src/password-policy.ts
new file mode 100644
index 000000000..918b21e31
--- /dev/null
+++ b/packages/toolkit/core-kit/src/password-policy.ts
@@ -0,0 +1,319 @@
+import crypto from 'node:crypto';
+
+import { z } from 'zod';
+
+/** A word that used for password policy. */
+type Word = {
+  type: 'custom' | 'personal';
+  value: string;
+};
+
+/** Password policy configuration type. */
+type PasswordPolicy = {
+  /** Policy about password length. */
+  length: {
+    /** Minimum password length. */
+    min: number;
+    /** Maximum password length. */
+    max: number;
+  };
+  /**
+   * Policy about password character types. Four types of characters are supported:
+   *
+   * - Lowercase letters (a-z).
+   * - Uppercase letters (A-Z).
+   * - Digits (0-9).
+   * - Symbols ({@link PasswordPolicyChecker.symbols}).
+   */
+  characterTypes: {
+    /** Minimum number of character types. Range: 1-4. */
+    min: number;
+  };
+  /** Policy about what passwords to reject. */
+  rejects: {
+    /** Whether to reject passwords that are pwned. */
+    pwned: boolean;
+    /** Whether to reject passwords that like '123456' or 'aaaaaa'. */
+    repetitionAndSequence: boolean;
+    /** Whether to reject passwords that include specific words. */
+    words: Word[];
+  };
+};
+
+/** Password policy configuration guard. */
+const passwordPolicyGuard: z.ZodType<PasswordPolicy> = z.object({
+  length: z.object({
+    min: z.number().int().min(1),
+    max: z.number().int().min(1),
+  }),
+  characterTypes: z.object({
+    min: z.number().int().min(1).max(4),
+  }),
+  rejects: z.object({
+    pwned: z.boolean(),
+    repetitionAndSequence: z.boolean(),
+    words: z.array(z.object({ type: z.enum(['custom', 'personal']), value: z.string() })),
+  }),
+});
+
+/** The code of why a password is rejected. */
+type PasswordRejectionCode =
+  | 'too_short'
+  | 'too_long'
+  | 'character_types'
+  | 'unsupported_characters'
+  | 'pwned'
+  | 'repetition'
+  | 'sequence'
+  | 'restricted_words';
+
+/** A password issue that does not meet the policy. */
+type PasswordIssue = {
+  /** Issue code. */
+  code: `password_rejected.${PasswordRejectionCode}`;
+  /** Interpolation data for the issue message. */
+  interpolation?: Record<string, unknown>;
+};
+
+/**
+ * The class for checking if a password meets the policy. The policy is defined as
+ * {@link PasswordPolicy}.
+ *
+ * @example
+ * ```ts
+ * const checker = new PasswordPolicyChecker({
+ *   length: { min: 8, max: 256 },
+ *   characterTypes: { min: 2 },
+ *   rejects: { pwned: true, repetitionAndSequence: true, words: [] },
+ * });
+ *
+ * const issues = await checker.check('123456');
+ * console.log(issues);
+ * // [
+ * //   { code: 'password_rejected.too_short' },
+ * //   { code: 'password_rejected.character_types', interpolation: { min: 2 } },
+ * //   { code: 'password_rejected.pwned' },
+ * //   { code: 'password_rejected.sequence' },
+ * // ]
+ * ```
+ */
+export class PasswordPolicyChecker {
+  static symbols = Object.freeze('!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~' as const);
+
+  constructor(public readonly policy: PasswordPolicy) {
+    // Validate policy.
+    passwordPolicyGuard.parse(policy);
+  }
+
+  /**
+   * Check if a password meets the policy.
+   *
+   * @param password - Password to check.
+   * @returns An array of issues. If the password meets the policy, an empty array will be returned.
+   */
+  /* eslint-disable @silverhand/fp/no-mutating-methods */
+  async check(password: string): Promise<PasswordIssue[]> {
+    const issues: PasswordIssue[] = [];
+
+    if (password.length < this.policy.length.min) {
+      issues.push({
+        code: 'password_rejected.too_short',
+      });
+    } else if (password.length > this.policy.length.max) {
+      issues.push({
+        code: 'password_rejected.too_long',
+      });
+    }
+
+    const characterTypes = this.checkCharTypes(password);
+    if (characterTypes === 'unsupported') {
+      issues.push({
+        code: 'password_rejected.unsupported_characters',
+      });
+    } else if (!characterTypes) {
+      issues.push({
+        code: 'password_rejected.character_types',
+        interpolation: { min: this.policy.characterTypes.min },
+      });
+    }
+
+    if (this.policy.rejects.pwned && (await this.hasBeenPwned(password))) {
+      issues.push({
+        code: 'password_rejected.pwned',
+      });
+    }
+
+    if (this.policy.rejects.repetitionAndSequence) {
+      if (this.hasRepetition(password)) {
+        issues.push({
+          code: 'password_rejected.repetition',
+        });
+      }
+
+      if (this.hasSequentialChars(password)) {
+        issues.push({
+          code: 'password_rejected.sequence',
+        });
+      }
+    }
+
+    issues.push(
+      ...this.hasWords(password).map<PasswordIssue>(({ type, value }) => ({
+        code: 'password_rejected.restricted_words',
+        interpolation: { type, value },
+      }))
+    );
+
+    return issues;
+  }
+  /* eslint-enable @silverhand/fp/no-mutating-methods */
+
+  /**
+   * Check if the given password contains enough character types.
+   *
+   * @param password - Password to check.
+   * @returns Whether the password contains enough character types; or `'unsupported'`
+   * if the password contains unsupported characters.
+   */
+  checkCharTypes(password: string): boolean | 'unsupported' {
+    const characterTypes = new Set<string>();
+    for (const char of password) {
+      if (char >= 'a' && char <= 'z') {
+        characterTypes.add('lowercase');
+      } else if (char >= 'A' && char <= 'Z') {
+        characterTypes.add('uppercase');
+      } else if (char >= '0' && char <= '9') {
+        characterTypes.add('digits');
+      } else if (PasswordPolicyChecker.symbols.includes(char)) {
+        characterTypes.add('symbols');
+      } else {
+        return 'unsupported';
+      }
+    }
+
+    return characterTypes.size >= this.policy.characterTypes.min;
+  }
+
+  /**
+   * Check if the given password has been pwned.
+   *
+   * @param password - Password to check.
+   * @returns Whether the password has been pwned.
+   */
+  async hasBeenPwned(password: string): Promise<boolean> {
+    const hash = await crypto.subtle.digest('SHA-1', new TextEncoder().encode(password));
+    const hashHex = Array.from(new Uint8Array(hash))
+      .map((binary) => binary.toString(16).padStart(2, '0'))
+      .join('');
+    const hashPrefix = hashHex.slice(0, 5);
+    const hashSuffix = hashHex.slice(5);
+    const response = await fetch(`https://api.haveibeenpwned.com/range/${hashPrefix}`);
+    const text = await response.text();
+    const hashes = text.split('\n');
+    const found = hashes.some((hex) => hex.toLowerCase().startsWith(hashSuffix));
+
+    return found;
+  }
+
+  /**
+   * Check if the given password contains repetition characters that are more than
+   * 4 characters or equal to the password length.
+   *
+   * @param password - Password to check.
+   * @returns Whether the password contains repetition characters.
+   */
+  hasRepetition(password: string): boolean {
+    const matchedRepetition = password.match(
+      new RegExp(`(.)\\1{${Math.min(password.length - 1, 4)},}`, 'g')
+    );
+
+    return Boolean(matchedRepetition);
+  }
+
+  /**
+   * Check if the given password contains specific words.
+   *
+   * @param password - Password to check.
+   * @returns An array of matched words.
+   */
+  hasWords(password: string): Word[] {
+    const words = this.policy.rejects.words.map(({ value, ...rest }) => ({
+      ...rest,
+      value: value.toLowerCase(),
+    }));
+    const lowercasedPassword = password.toLowerCase();
+
+    return words.filter(({ value }) => lowercasedPassword.includes(value));
+  }
+
+  /**
+   * Check if the given password contains sequential characters, and the number of
+   * sequential characters is over 4 or equal to the password length when (1 < length < 5).
+   *
+   * @param password - Password to check.
+   * @returns Whether the password contains sequential characters.
+   *
+   * @example
+   * ```ts
+   * hasSequentialChars('1'); // false
+   * hasSequentialChars('12345'); // true
+   * hasSequentialChars('123456@Bc.dcE'); // true
+   * hasSequentialChars('123@Bc.dcE'); // false
+   * ```
+   */
+  // Disable the mutation rules because the algorithm is much easier to implement with
+  /* eslint-disable @silverhand/fp/no-let, @silverhand/fp/no-mutation, @silverhand/fp/no-mutating-methods */
+  hasSequentialChars(password: string): boolean {
+    let sequence: number[] = [];
+
+    for (const char of password) {
+      // Always true
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      const charCode = char.codePointAt(0)!;
+
+      if (sequence.length === 0) {
+        sequence.push(charCode);
+        continue;
+      }
+
+      if (
+        this.checkSequentialWithChar(sequence, charCode, 1) ||
+        this.checkSequentialWithChar(sequence, charCode, -1)
+      ) {
+        sequence.push(charCode);
+      } else {
+        sequence = [charCode];
+      }
+
+      if (sequence.length >= 5 || sequence.length === password.length) {
+        return true;
+      }
+    }
+
+    return false;
+  }
+  /* eslint-enable @silverhand/fp/no-let, @silverhand/fp/no-mutation, @silverhand/fp/no-mutating-methods */
+
+  /**
+   * Check if the given char code will be sequential after appending to the given
+   * char code array.
+   */
+  protected checkSequentialWithChar(
+    current: Readonly<number[]>,
+    newCharCode: number,
+    direction: 1 | -1
+  ): boolean {
+    const lastCharCode = current.at(-1);
+
+    if (newCharCode - direction === lastCharCode) {
+      if (current.length === 1) {
+        return true;
+      }
+      if (current.at(-2) === newCharCode - direction * 2) {
+        return true;
+      }
+    }
+
+    return false;
+  }
+}