JWT Decoder & Inspector

Inspect JSON Web Token (JWT) headers, custom claims, expiration dates, and signatures securely.

About JWT Decoder & Inspector

The JWT Decoder & Token Inspector is an offline, privacy-first security tool that parses encoded JSON Web Tokens (RFC 7519) into readable, structured JSON components: the Header (algorithm and token type), the Payload (standard claims such as iss, sub, aud, exp, nbf, iat, plus custom claims), and the Signature digest. Ideal for debugging OAuth 2.0 / OpenID Connect tokens, Supabase, Firebase, Auth0, and Cognito authentication sessions without exposing private bearer tokens to external networks.

Key features

• Complete Tri-Part Token Deconstruction: Distinctly colors and separates the Header (JOSE), Payload (Claims), and Signature
• Human-Readable Timestamp Formatting: Automatically converts raw Unix epoch timestamps (exp, iat, nbf) into localized date-time strings
• Expiration Status Detection: Instantly flags whether a token is active, expired, or not yet valid based on system clock time
• Zero Network Exposure: Operates strictly client-side using base64url decoding; tokens are never logged or transmitted

How to use

• Paste JSON Web Token: Paste your compact three-part (dot-separated) JWT string into the token input editor.
• Inspect Claims & Expiration: Examine decoded JOSE headers, standard registered claims, user attributes, and expiration status.
• Copy Formatted JSON Claims: Click "Copy" next to the Header or Payload panel to copy the formatted JSON object to your clipboard.

FAQ

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