Online JWT Converter

This tool decodes a JSON Web Token (JWT) into its header and payload for inspection and auditing. It performs base64url decoding and JSON parsing to reveal claims such as iss, sub, aud, exp, and iat, along with the signing algorithm. It can also extract the signature and detect the algorithm used.
If a secret or public key is supplied, the tool can verify the signature by recomputing the signing input and applying the specified algorithm (HS256, RS256, ES256, etc.). It returns a validity flag and diagnostic details that help identify mismatches between the token and the provided key or algorithm.
Intended for developers, QA engineers, security analysts, and API integrators, the tool supports token inspection during integration, debugging, and security reviews. It handles common edge cases such as malformed tokens, missing segments, invalid base64url, and unsupported algorithms, while offering clear output formats for further processing.
Core value lies in transparency and speed: you can decode without network calls, verify offline with a provided key, and export structured results for logs or tooling pipelines.