/**
 * Provides platform-aware base64 encoding utilities.
 *
 * @remarks
 * This module provides base64 encoding/decoding operations across Node.js and browser
 * environments. For hex and string conversions, use viem's utilities directly:
 * - `toHex` / `fromHex` from 'viem'
 * - `stringToBytes` / `bytesToString` from 'viem'
 *
 * @category Utilities
 */
/**
 * Converts a Uint8Array to a base64 string.
 *
 * @param data - The byte array to encode into base64 format.
 * @returns The base64-encoded string representation.
 * @throws {Error} When no base64 encoding method is available in the environment.
 *
 * @example
 * ```typescript
 * const bytes = new Uint8Array([72, 101, 108, 108, 111]);
 * const encoded = toBase64(bytes);
 * console.log(encoded); // "SGVsbG8="
 * ```
 */
export declare function toBase64(data: Uint8Array): string;
/**
 * Converts a base64 string to a Uint8Array.
 *
 * @param str - The base64-encoded string to decode.
 * @returns The decoded byte array.
 * @throws {Error} When no base64 decoding method is available in the environment.
 *
 * @example
 * ```typescript
 * const decoded = fromBase64("SGVsbG8=");
 * console.log(new TextDecoder().decode(decoded)); // "Hello"
 * ```
 */
export declare function fromBase64(str: string): Uint8Array;
/**
 * Type guard to check if running in Node.js environment
 *
 * @returns True if running in Node.js
 */
export declare function isNodeEnvironment(): boolean;
/**
 * Type guard to check if running in browser environment
 *
 * @returns True if running in browser
 */
export declare function isBrowserEnvironment(): boolean;