/**
 * Decode a base64url string to Uint8Array
 * RFC 4648 §5 - Base64 URL-safe encoding
 */
export declare function base64urlDecode(input: string): Uint8Array;
/**
 * Encode Uint8Array to base64url string
 */
export declare function base64urlEncode(bytes: Uint8Array): string;
/**
 * Decode base64url to UTF-8 string
 */
export declare function base64urlDecodeString(input: string): string;
/**
 * Parse a JWT token into its parts (header, payload, signature)
 * Does NOT verify the signature
 */
export declare function parseJWT(token: string): {
    header: Record<string, unknown>;
    payload: Record<string, unknown>;
    signature: Uint8Array;
    signedContent: string;
} | null;
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