/**
 * Custom validation utilities to replace Sequelize's validator
 */
/**
 * Validates if a string is a valid email address
 * @param value - The string to validate
 * @returns boolean - True if valid email, false otherwise
 */
export declare const isEmail: (value: string) => boolean;
/**
 * Validates if a string is a valid URL
 * @param value - The string to validate
 * @returns boolean - True if valid URL, false otherwise
 */
export declare const isURL: (value: string) => boolean;
/**
 * Validates if a string is a valid date
 * @param value - The string to validate
 * @param format - Optional date format (default: YYYY-MM-DD)
 * @returns boolean - True if valid date, false otherwise
 */
export declare const isDate: (value: string, format?: string) => boolean;