Secure JWT Decoder

Decode and debug JSON Web Tokens instantly with complete privacy

Paste Your JWT Token

100% client-side • No server communication • Your data never leaves your browser

Security First

Your JWT tokens contain sensitive authentication data. That's why our decoder runs entirely in your browser with zero server communication.

🔒

No Server Communication

Your JWT is decoded entirely in your browser using JavaScript. Zero network requests are made.

🚫

No Data Storage

We don't store, log, or cache your tokens anywhere. Clear the input and it's gone from memory.

🔓

No Secret Key Required

JWTs can be decoded without the secret key. We only decode—we don't verify signatures.

🛡️

Open Source Logic

The decoding logic is transparent and follows JWT RFC 7519 standards using trusted libraries.

What is a JWT?

JSON Web Token (JWT) is an open standard (RFC 7519) for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed.

Header

Contains the token type (JWT) and the signing algorithm (e.g., HS256, RS256).

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

Payload

Contains the claims—statements about the user and additional metadata (e.g., user ID, expiration time).

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

Signature

Created by encoding the header and payload, then signing with a secret key. Ensures the token hasn't been tampered with.

HMACSHA256(base64UrlEncode(header) + '.' + base64UrlEncode(payload), secret)

How It Works

Paste JWT Token

Paste your JWT token into the input field

Instant Decoding

The token is decoded instantly in your browser

View Breakdown

See color-coded Header, Payload, and Signature sections

Key Features

100% Client-Side Processing

All decoding happens entirely in your browser's memory. Your JWT never leaves your device or gets sent to any server.

Visual Color-Coded Breakdown

Three distinct sections (Header, Payload, Signature) with industry-standard color coding for instant recognition.

Expiration Validation

Automatically checks if your token is expired by comparing the exp claim with the current timestamp.

Human-Readable Dates

Converts Unix timestamps (iat, exp, nbf) to readable local date/time formats for easy understanding.

Copy Individual Parts

Copy just the header, payload, or signature separately for debugging or documentation purposes.

Format Validation

Instantly validates JWT format and displays clear error messages for malformed tokens.

Common Use Cases

API Authentication Debugging

Debug authorization issues by inspecting JWT tokens returned from your APIs.

Token Expiration Checks

Quickly verify if authentication failures are due to expired tokens.

OAuth & SSO Testing

Examine ID tokens and access tokens from OAuth providers like Auth0, Okta, or Firebase.

JWT Learning & Education

Understand JWT structure and claims by decoding real-world examples.

Why Choose Our JWT Decoder?

Instant Results

No page reloads or server delays. Decode JWTs in milliseconds as you type.

Works Offline

Once loaded, the tool works completely offline. No internet connection needed.

No Rate Limits

Decode unlimited tokens. No registration, no API keys, no restrictions.

Mobile Friendly

Fully responsive design that works perfectly on phones, tablets, and desktops.

Pro Tips

💡 Understanding JWT Structure

JWTs have three parts separated by dots (.). The first part is the header, second is the payload, and third is the signature.

💡 Decoding vs. Verifying

Decoding reads the token contents without checking its validity. Verifying requires the secret key and should only be done server-side.

💡 Check Expiration Claims

Always check the 'exp' (expiration) claim. An expired token will be rejected by your server even if it looks valid.

💡 Sensitive Data Warning

Never put sensitive data in JWT payloads. They're base64-encoded, not encrypted—anyone can decode them.

Frequently Asked Questions

🔐What is a JWT (JSON Web Token)?

A JWT is a compact, URL-safe token format used for securely transmitting information between parties. It consists of three parts: a header (token type and algorithm), a payload (claims/data), and a signature (verification hash). JWTs are commonly used for authentication and authorization in modern web applications.

🔒Is it safe to paste my JWT token here?

Yes! This tool runs entirely in your browser using client-side JavaScript. Your JWT is never sent to any server, stored in any database, or logged anywhere. Once you clear the input or close the page, the token is completely removed from memory. You can even disconnect from the internet and the tool will still work.

✍️Why don't you verify the JWT signature?

Signature verification requires the secret key, which should NEVER be exposed to the browser or client-side code. Our tool only decodes the token to show its contents. For signature verification, use your backend/server where the secret key is securely stored. This approach maintains the 'decode-only' privacy guarantee.

⏰What does 'Token Expired' mean?

JWTs contain an 'exp' (expiration) claim—a Unix timestamp indicating when the token expires. If the current time is past this timestamp, the token is expired and servers will reject it. You'll need to request a new token from your authentication provider.

🌐Can I decode JWTs from any provider?

Yes! This tool works with JWTs from any provider (Auth0, Firebase, AWS Cognito, Okta, custom backends, etc.) as long as they follow the JWT RFC 7519 standard. The tool automatically handles different algorithms (HS256, RS256, etc.) for decoding.

⚠️Why is my JWT showing an error?

Common errors include: incomplete token (missing parts), invalid base64 encoding, or non-JWT format. Ensure you've copied the entire token including all three parts separated by dots. JWTs should look like: xxxxx.yyyyy.zzzzz