Your token is decoded entirely in your browser — never sent to any server.
Ready to inspect
Paste a JWT token and click Inspect// decode jwt structure and inspect claims locally
Decode and inspect JWT tokens locally in your browser. View headers, claims, expiry, issued-at, audience, and all standard fields instantly — no server upload.
Ready to inspect
Paste a JWT token and click InspectCopy your JSON Web Token from your app, API response, or auth header and paste it into the input field.
Hit the Inspect Token button. The tool decodes header and payload instantly in your browser — nothing leaves your machine.
Switch between Summary, Header, and Payload tabs to see all claims, expiry status, issued-at time, and algorithm details.
JWT Claims Inspector decodes any JSON Web Token and presents its structure in a clear, readable format. It shows the JOSE header (algorithm, type), all registered claims (exp, iat, nbf, iss, sub, aud, jti), and any custom claims — all processed locally with zero network requests.
Absolutely not. All decoding happens entirely in your browser using JavaScript. No data — not even a single character — is transmitted to any server. You can disconnect from the internet and the tool will still work perfectly.
No — and that's intentional for security. Signature verification requires your secret key or public key, which you should never paste into a third-party tool. This inspector decodes and displays the header and payload only. Always verify signatures server-side using a trusted library.
The inspector displays whichever algorithm is declared in the JWT header — HS256, HS384, HS512, RS256, RS384, RS512, ES256, ES384, ES512, PS256, PS384, PS512, and none. Since decoding (not verifying) is algorithm-agnostic, all JWTs are supported.
Standard registered claims include: iss (Issuer), sub (Subject), aud (Audience), exp (Expiration Time), nbf (Not Before), iat (Issued At), and jti (JWT ID). Any other claims are private or public custom claims specific to your application.
Paste the token and click Inspect. The Summary tab shows a clear Expiry status indicator — green for valid, red for expired, yellow for not-yet-valid (nbf). It also shows the exact expiry date/time and how many minutes/hours remain or have passed.
Yes. If you paste a JWT with two parts (header.payload) the tool will still decode the header and payload. Only the signature section will be marked as absent. This is sometimes seen with alg: "none" tokens, which are considered insecure for production use.
JWT (JSON Web Token) is the general concept. JWS (JSON Web Signature) is a signed JWT — the most common form, with a verifiable signature. JWE (JSON Web Encryption) is an encrypted JWT where the payload itself is encrypted and not readable without the decryption key. This tool handles JWS tokens; JWE payloads will appear as encrypted ciphertext.
Since no data leaves your browser, the risk is minimal compared to server-based decoders. However, best practice is to use non-production or expired tokens when debugging. JWTs often contain user identifiers and claims that should be treated as sensitive data, even in development environments.
A JWT Claims Inspector is a developer tool that decodes the three-part structure of a JSON Web Token (JWT) and presents the contents in a human-readable format. JWTs are a compact, URL-safe means of representing claims to be transferred between two parties. They are widely used in authentication systems, API authorization, and single sign-on (SSO) implementations.
Unlike a JWT verifier, a claims inspector focuses on readability — breaking down the base64url-encoded header and payload so developers can quickly understand what a token contains, when it was issued, when it expires, and which service issued it.
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Every JWT consists of three parts separated by dots (.): the Header, the Payload, and the Signature. Each part is independently base64url-encoded.
typ, usually JWT) and the signing algorithm (alg), such as HS256, RS256, or ES512.The JWT specification (RFC 7519) defines a set of registered claim names that have predefined meanings. Understanding each claim is essential for debugging authentication flows:
iss (Issuer) — Identifies the principal that issued the JWT. This is typically the URL of your auth server or identity provider.sub (Subject) — Identifies the principal that is the subject of the JWT. Usually a user ID or account identifier.aud (Audience) — Identifies the recipients that the JWT is intended for. Can be a string or an array of strings representing one or multiple intended consumers.exp (Expiration Time) — The time after which the JWT must not be accepted. Stored as a Unix timestamp (seconds since epoch).nbf (Not Before) — The time before which the JWT must not be accepted. Useful for scheduling tokens that activate in the future.iat (Issued At) — The time at which the JWT was issued. Useful for determining the age of the token.jti (JWT ID) — A unique identifier for the JWT. Used to prevent replay attacks by tracking which IDs have already been consumed.The algorithm declared in the JWT header determines how the signature is created and verified:
alg: none should be treated with extreme caution.There are many practical reasons a developer needs to inspect JWT claims during the development lifecycle:
iat, nbf, and exp timestamps helps diagnose time-related validation failures that occur when server clocks are out of sync.Decoding a JWT's header and payload requires only base64url-decoding — no secret or key is needed. This makes it perfectly safe to do client-side. Our JWT Claims Inspector performs all decoding locally in your browser using standard JavaScript, with zero network requests.
Signature verification, on the other hand, must be done server-side using a trusted library and the appropriate key material. Never trust a JWT's claims without verifying its signature on the server before granting access to protected resources.
When working with JWTs in your applications, keep these security principles in mind:
exp) and implement token refresh flows.localStorage in security-sensitive applications — prefer httpOnly cookies.aud claim to prevent token substitution attacks.alg: none at the server level.