JWT (JSON Web Token) is an open standard (RFC 7519) for securely transmitting information between parties as a JSON object. It consists of three parts: header, payload, and signature, separated by dots.

Is it safe to decode a JWT token online?

Yes, when using JSON Web Tools. All JWT decoding happens entirely in your browser - your token is never sent to any server. You can even use it offline after the first load.

Can I verify a JWT signature online?

You can inspect and decode the JWT payload without the secret key. To verify the signature you need the original secret or public key. Our tool shows the algorithm and lets you inspect all claims.

What information is in a JWT payload?

JWT payloads typically contain claims like sub (subject/user ID), iat (issued at), exp (expiration), and custom claims like roles or permissions. Note: JWT payloads are base64 encoded, not encrypted - never put sensitive data in them.

JWT Decoder Online

Instantly decode any JWT token - see the header, payload, and signature breakdown. Free, private, no signup required.

Open JWT Decoder →

What is a JWT Token?

A JSON Web Token (JWT) is a compact, URL-safe token format defined by RFC 7519. It is the most widely used authentication format in modern web applications, REST APIs, and microservices. Every JWT consists of three base64url-encoded parts separated by dots:

Header - Algorithm (HS256, RS256, etc.) and token type
Payload - Claims: user ID, roles, expiry, custom data
Signature - Cryptographic proof of authenticity

Example: eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1c2VyMTIzIn0.signature

How to Decode a JWT Token Online

Copy your JWT token (from browser DevTools, Postman, or your app)
Click "Open JWT Decoder" above
Paste the token into the input field
The header, payload, and signature are instantly decoded
Inspect claims like exp, iat, sub, roles

Common JWT Claims Explained

Claim	Meaning	Example
`sub`	Subject (user ID)	"user_123"
`iat`	Issued at (Unix timestamp)	1709000000
`exp`	Expiration time	1709086400
`iss`	Issuer (who created it)	"api.myapp.com"
`aud`	Audience (intended recipient)	"myapp.com"

JWT Security Best Practices

Never store sensitive data in payload - JWT is base64 encoded, not encrypted. Anyone can decode it.
Always verify the signature on the server side before trusting any claims.
Set short expiration times - Use exp claim and implement refresh tokens.
Use HTTPS only - Never transmit JWTs over plain HTTP.
Avoid storing in localStorage for high-security apps - use HttpOnly cookies instead.
Use strong algorithms - Prefer RS256 (asymmetric) over HS256 for public APIs.

Frequently Asked Questions

What is a JWT?

A JWT (JSON Web Token) is a compact, URL-safe string used to securely transmit information between parties. It has three parts separated by dots: a Base64Url-encoded header, a Base64Url-encoded payload, and a signature. JWTs are commonly used for authentication in web applications.

Is it safe to decode a JWT online?

The payload of a JWT is Base64Url encoded, not encrypted — anyone with the token can decode it. Decoding is safe since it doesn't require the secret key. However, never paste production JWTs containing sensitive user data into online tools. Use test tokens for debugging.

Can this tool verify the JWT signature?

The decoder shows the decoded header and payload instantly. Signature verification requires the secret key (for HMAC) or public key (for RSA/ECDSA). The tool can check if the token is expired by reading the exp claim, but cannot cryptographically verify the signature without the key.

What does exp mean in a JWT?

The exp (expiration time) claim is a Unix timestamp indicating when the token expires. The iat (issued at) claim shows when it was created. The nbf (not before) claim indicates the earliest time the token is valid. Our decoder converts all three to human-readable dates.

What signing algorithms do JWTs use?

The most common JWT algorithms are: HS256/HS384/HS512 (HMAC with SHA), RS256/RS384/RS512 (RSA with SHA), ES256/ES384/ES512 (ECDSA), and PS256/PS384/PS512 (RSASSA-PSS). The algorithm is declared in the JWT header's alg field.

How do I create a JWT?

JWTs are generated server-side using a library: jsonwebtoken (Node.js), PyJWT (Python), or java-jwt (Java). You define the payload claims, choose an algorithm, sign with your secret or private key, and the library produces the encoded token string.

Ready to decode your JWT?

Free, instant, 100% private. No account needed.

Open JWT Decoder →

Also useful: JSON Tutorials & Guides | FAQ | JSON Validator | JSON to TypeScript