JWT Decoder

Inspect JSON Web Token (JWT) headers, payload claims, issued-at (iat), and expiration (exp) timestamps 100% client-side in your browser without exposing production tokens over the network.

100% freeNo sign-upRuns in your browser

Paste JWT Token (Decoded 100% locally in your browser)

Header (Algorithm & Token Type)

{
  "alg": "HS256",
  "typ": "JWT"
}

Payload (Claims & Data)

{
  "sub": "1234567890",
  "name": "John Doe",
  "iat": 1516239022,
  "exp": 1916239022
}

Issued At (iat): Thu, 18 Jan 2018 01:30:22 GMTExpires (exp): Sat, 21 Sep 2030 16:37:02 GMT Valid

About the JWT Decoder

A JSON Web Token (JWT) decoder unpacks and displays the header and payload claims stored within a JWT string. JWTs are compact, URL-safe tokens widely used for authentication, Single Sign-On (SSO), and secure data exchange between modern web clients and APIs.

A standard JWT consists of three Base64URL-encoded parts separated by periods: the Header (containing the token type and signing algorithm, such as HS256 or RS256), the Payload (containing claims like subject user ID, issuer, roles, and expiration timestamp), and the cryptographic Signature.

This tool operates entirely client-side in your browser. Because tokens frequently contain sensitive user IDs, roles, and permissions, in-browser decoding ensures your private session tokens are never transmitted to external servers. It also translates UNIX epoch timestamps (`exp`, `iat`, `nbf`) into human-readable dates, instantly revealing whether a token is expired.

Worked example: Inspecting token claims

Pasting an authentication token reveals its header `{"alg": "HS256", "typ": "JWT"}` and decoded claims payload `{"sub": "usr_10924", "name": "Alex", "role": "admin", "exp": 1791280000}`, demonstrating valid administrator access.

Tips for best results

Remember that standard JWT payloads are merely Base64URL-encoded, NOT encrypted; anyone with access to the token can inspect its claims. Never store sensitive secrets or passwords in a JWT payload.
Always check the 'exp' (expiration) claim to verify whether an authentication token has expired.
Verification of cryptographic signatures must always occur on your secure backend server using your private secret key.

How to use the JWT Decoder

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Why use Toolseza for JWT Decoder?

100% Free & Unlimited

Use this tool as often as you need with no paywalls, premium tiers, or hidden daily calculation quotas.

Strict Privacy by Design

All calculations and file manipulations run inside your web browser. Your inputs are never sent to a cloud server.

Instant Reactive Results

Results update in real-time as you type or adjust settings, with instant one-click copy and export capabilities.

No App or Signup Needed

Works natively on smartphones, tablets, laptops, and desktop computers with zero installation or account creation.

Editorial Standards & Verification: All formulas, algorithms, and conversion factors implemented on Toolseza adhere to openly documented international standards (ISO, NIST, BIPM, W3C). Results are verified against benchmark reference datasets before publication.