JWT Decoder & Inspector Online
Decode, inspect, and debug JSON Web Tokens (JWT) directly in your browser. Inspect JOSE headers, payload claims, and token expiration dates client-side with zero data transmitted to external servers.
How to Decode and Inspect a JWT
- 1
Paste encoded token
Paste your raw JWT string (beginning with ey...) into the input container or click Load Sample Token.
- 2
Inspect header and payload
Review the parsed Header to see the cryptographic algorithm (alg) and examine the Payload claims.
- 3
Check expiration badge
Observe the expiration badge to verify whether the token is currently active or has expired according to its exp claim.
JWT Inspector Features
Instant Header & Payload Parsing
Decodes Base64URL parts into color-coded, cleanly indented JSON representations of headers and payload claims.
Automatic Expiration Status
Reads the standard "exp" timestamp claim and checks it against your local clock to clearly flag valid vs expired tokens.
Claim Inspection
Easily inspect standard registered claims (iss, sub, aud, iat, exp) alongside custom user metadata and role arrays.
Client-Side Privacy Guarantee
Tokens are processed entirely within browser memory; authentication credentials and session tokens are never transmitted to backend servers.
Sample Token Loader
Quickly load an example JWT with a single click to test inspection features and explore token anatomy.
Formatted Clipboard Export
Copy decoded header or payload JSON blocks individually with convenient copy buttons.
What is a JWT and How Does Decoding Work?
A JSON Web Token (JWT) is an open industry standard (RFC 7519) for securely transmitting information between parties as a compact, self-contained JSON object. A standard JWT comprises three Base64URL-encoded parts separated by periods: the Header (identifying the signing algorithm), the Payload (containing user identity and session claims), and the Signature.
Because the Header and Payload are Base64URL encoded rather than encrypted, anyone in possession of a token can decode and read its contents. A JWT Decoder translates these encoded strings back into clean, formatted JSON so you can inspect claims such as issuer (iss), subject (sub), audience (aud), and expiration time (exp).
Important Security Distinction: Decoding a JWT is NOT the same as verifying its cryptographic signature. Decoding merely displays the claims encoded within the token. Cryptographic verification requires validating the signature against the issuing server shared secret (HMAC) or public key (RSA/ECDSA) to guarantee the token has not been tampered with.
Frequently Asked Questions
Related Tools
Explore complementary utilities to speed up your workflow.
JSON Formatter
Format, beautify, validate, and inspect JSON online with instant syntax error detection. Free JSON formatter for developers.
Base64 Encoder/Decoder
Encode text to Base64 or decode Base64 strings online instantly. Free Base64 encoder and decoder for developers.