What Is a JWT Decoder? A JWT decoder is a specialized tool that extracts and displays the readable content hidden inside JSON Web Tokens. These tokens are widely used across modern web applications for authentication and authorization, but their encoded format makes them difficult to read without proper decoding. Think of a JWT decoder as a translator. When you receive a JWT token—which looks like a long string of random characters—the decoder breaks it apart and shows you exactly what information it contains. This includes details about the user, when the token expires, who issued it, and what permissions they have. The decoder works by reversing a simple encoding process called Base64URL encoding. This encoding is not encryption—it simply transforms the data into a URL-safe format. Anyone with a decoder can read the contents, which is why understanding how and when to use a JWT decoder is critical for both developers and anyone working with web security. Why JWT Decoders Exist: Th...