import { PassThrough } from 'stream';
/**
 * Read image url and convert to {Buffer}
 * @returns {Promise<Buffer | null>}
 */
export declare function getBufferFromUrl(url: string): Promise<Buffer<any> | null>;
export declare function getFileSizeFromUrl(url: string): Promise<number | null>;
/**
 * Read file url and convert to {ReadStream}
 */
export declare function getStreamFromUrl(url: string): Promise<{
    stream: PassThrough;
    size: number;
}>;
/**
 * Download file from url and save to outputPath
 * @param url
 * @param outputPath - Include file name
 * @returns {Promise<string | null>}
 */
export declare function downloadFile(url: string, outputPath: string): Promise<string | null>;