JWT Decoder (JSON Web Token)
Decode and inspect JWTs with header, payload, signature & validation.
JWT Decoder & Validator Tool
Decode JSON Web Tokens instantly. Inspect header, payload, signature, validate HS256 tokens, and debug authentication issues — all securely in your browser.
What is a JWT (JSON Web Token)?
A JSON Web Token (JWT) is a compact, URL-safe string used for securely transmitting information between parties. JWTs are widely used for authentication, API authorization, single sign-on (SSO), and secure data exchange.
A JWT consists of three parts separated by dots:
JWT Structure Explained
Header
Contains token type and signing algorithm (e.g., HS256, RS256).
Payload
Includes claims such as user ID, permissions, expiry time (exp), and issued time (iat).
Signature
Verifies token integrity and authenticity using a secret or public/private key pair.
Is It Safe to Decode a JWT?
Yes. Decoding a JWT only reveals its header and payload — it does not expose secret keys. However, decoding alone does not verify authenticity. Always validate the signature before trusting a token.
HS256 vs RS256 – JWT Signing Algorithms
| Feature | HS256 | RS256 |
|---|---|---|
| Type | Symmetric | Asymmetric |
| Key Used | Shared secret | Private + Public key |
| Best For | Internal services | Public APIs & OAuth |
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