About this tool

ToolAdda's JWT Debugger is a free, browser-based developer tool that decodes JSON Web Tokens, inspects headers, payloads and claims, checks expiration, and performs automated security analysis. It supports real cryptographic signature verification for HS256, RS256, PS256 and ES256 using the native Web Crypto API, with all processing done client-side so tokens and keys are never uploaded. Ideal for debugging authentication flows, validating tokens and learning JWT internals.