/// <reference types="validator" />
import _isBase64 from 'validator/lib/isBase64';
import { TReferenceProps } from '../../..';
import { IStringProps, TStringValidatorResult } from '../_types';
declare type TParameters = Parameters<typeof _isBase64>;
export interface IIsBase64Props {
    /**
     * `options` is optional and defaults to `{ urlSafe: false }`.
       When `urlSafe` is `true` it tests the given base64 encoded string is [url safe](https://base64.guru/standards/base64url).
     */
    options?: TParameters[1];
}
/**
 * Check if a string is base64 encoded.
 */
export declare const isBase64: (props?: TReferenceProps<IIsBase64Props> & IStringProps) => TStringValidatorResult;
export {};