/**
 * Portable base64 helpers that work in Node, Bun, Deno, browsers, and edge
 * runtimes (Cloudflare Workers, Vercel Edge). Avoids reliance on Node's
 * `Buffer` global.
 */
export declare function encodeBase64Ascii(input: string): string;
/**
 * Base64-encode a UTF-8 TEXT string. Unlike {@link encodeBase64Ascii} (which
 * treats each code unit as a raw byte and therefore corrupts / throws on
 * non-ASCII), this first serializes to UTF-8 bytes so `café`/emoji survive the
 * round-trip. Use this for any email content/MIME payload; reserve
 * `encodeBase64Ascii` for guaranteed-ASCII credential strings (`user:pass`).
 */
export declare function encodeBase64Utf8(input: string): string;
export declare function encodeBase64Bytes(input: Uint8Array | ArrayBuffer): string;