JWT Decoder Online - Decode JSON Web Tokens Instantly

What is a JWT Decoder?

A JWT decoder takes a JSON Web Token and shows you the human-readable content inside it. You often see these long strings separated by dots in authorization headers and cookies.

A standard JWT looks like this:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIn0.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

It consists of three parts separated by dots:

1. Header: This contains the token type and signing algorithm, such as HS256 or RS256.
2. Payload: These are the actual claims, which might include a user ID, roles, expiration time, issuer, and any custom fields.
3. Signature: The server uses this to verify the token’s integrity.

Each part is Base64URL-encoded, which explains why it looks like unreadable text. This decoder converts those encoded parts back into clear JSON.

How to Use

1. Paste your token: Copy the JWT from your browser’s developer tools, an API response, or your application logs.
2. Read the decoded output: The header and payload will appear as formatted JSON.
3. Check the claims: Verify the expiration time, subject or user ID, issuer, audience, and any custom claims to ensure they are correct.

Use Cases

• Debugging authentication errors: When you receive a 401 Unauthorized response, decode the JWT to check whether it has expired, been issued by the wrong service, or is missing required claims.
• OAuth 2.0 and OpenID Connect: Verify that access tokens or ID tokens contain the expected scopes and user information.
• API development: Confirm that your backend is signing and issuing tokens with the correct payload structure before releasing a new feature.
• SSO troubleshooting: Inspect tokens passed between microservices in a single sign-on flow to spot missing or malformed claims.
• Learning JWT structure: Understand how JWTs work by inspecting real tokens during local development.

Why Use This Tool?

Our JWT decoder processes your token entirely in the browser using JavaScript. Absolutely no data is transmitted to our servers. This local processing makes it safe to paste tokens that carry user session data or access credentials. You do not have to worry about the privacy risks associated with cloud-based tools that might log or store submitted tokens.