Encoders & Decoders
JWT Decoder
Inspect JWT headers and payloads instantly. Validate HS256 signatures on-device without sharing tokens.
Works offline for decoding and HS256 verification. Useful for quickly auditing claims during debugging.
Token parts0
VerificationNot checked
Secret keyMissing
Verify Signature (HS256 only)
Note: Only HS256 algorithm is supported for browser-based verification. RS256 and other algorithms require server-side verification.
What is a JWT (JSON Web Token)?
A JSON Web Token (JWT) is a compact, URL-safe means of representing claims to be transferred between two parties. It is an open standard (RFC 7519) that defines a self-contained way for securely transmitting information as a JSON object. This information can be verified and trusted because it is digitally signed.
How to Use the JWT Decoder
- Paste Token: Paste your JWT token into the input field.
- Instant Decoding: The header and payload are automatically decoded and displayed.
- Verify Signature: To verify the signature, enter the secret key and click "Verify Signature". Note that only the HS256 algorithm is supported for in-browser verification.
- Copy Parts: You can copy the header, payload, or signature to your clipboard with a single click.
JWT Structure
A JWT consists of three parts separated by dots (.):
- Header: Typically consists of two parts: the type of the token, which is JWT, and the signing algorithm being used, such as HMAC SHA256 or RSA.
- Payload: Contains the claims. Claims are statements about an entity (typically, the user) and additional data. There are three types of claims: registered, public, and private claims.
- Signature: To create the signature part, you have to take the encoded header, the encoded payload, a secret, the algorithm specified in the header, and sign that.
Why Use This JWT Decoder?
- ✅ Instant Decoding: Decode JWTs in real-time without any server requests.
- 🔒 Client-Side Security: Your tokens are processed in your browser and never sent to a server, ensuring privacy.
- 📋 Easy Copying: Copy the decoded header, payload, or signature with a single click.
- 🐛 Debugging Made Easy: Perfect for debugging authentication flows and inspecting token contents.
- 💯 Free and Unlimited: A free and powerful alternative to other online JWT tools like jwt.io.