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🔐 Encoding & Security ✅ 100% Free ⚡ Instant

JWT Decoder

Decode and inspect any JSON Web Token. View the header algorithm, all payload claims, expiry status (valid or expired), and issuer — all without needing the secret key.

Paste a JWT token above.
📖 Standard Claims
subSubject (user ID)
issIssuer
audAudience
expExpiry timestamp
iatIssued at
nbfNot before
jtiJWT unique ID
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What is a JWT?

A JSON Web Token (JWT) is a compact, URL-safe way to represent claims between two parties. It has three Base64URL-encoded parts separated by dots: a header (algorithm and token type), a payload (claims about the user and token), and a signature (for verifying the token was not tampered with). JWTs are widely used for stateless authentication in REST APIs and single-page applications.

Frequently Asked Questions

The header and payload are simply Base64URL-encoded — anyone can decode them. The signature prevents tampering. Never store sensitive data in JWT payloads since they can be decoded by anyone with the token. Verification requires the secret key, which this tool does not do.
HS256 uses a shared secret key — same key to sign and verify. RS256 uses public/private key pair — server signs with private key, clients verify with public key. RS256 is more secure for distributed systems since you never share the signing key.
JWTs are stateless — once issued the server cannot invalidate them. Expiry limits damage if a token is stolen. Short expiry (15–60 min) is recommended for access tokens. Use refresh tokens with longer lifetimes to get new access tokens.
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About This JWT Decoder

JWT encoding is widely used in data transmission, URL handling, authentication tokens, and file storage. This free online JWT Decoder lets you instantly encode plain text or binary data into JWT format — or decode JWT strings back to their original form — all in your browser.

How to use

  1. Paste your input text or data into the input field.
  2. Click Encode or Decode depending on your need.
  3. Copy the result from the output panel.

Common use cases

Everything runs client-side in your browser. Your sensitive data is never uploaded or stored anywhere.

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Frequently Asked Questions

Is this JWT Decoder free to use? +
Yes, completely free. No signup, no account, no payment required. Just paste your input and use it directly in your browser.
Does this tool store or send my data anywhere? +
No. Everything runs entirely in your browser using JavaScript. Your data never leaves your device or gets sent to any server.
What browsers does this tool support? +
It works in all modern browsers — Chrome, Firefox, Safari, Edge, and Opera — on both desktop and mobile.
Can I use this tool offline? +
Once the page is loaded, the tool runs locally in your browser without needing an active internet connection for most operations.
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Custom Development

Need a Custom Version of This Tool?

This JWT Decoder works for most use cases — but if you need batch processing, API access, private hosting on your own domain, or a completely bespoke tool built around your workflow, I can build it.

Request Custom Build → Typical turnaround: 3–7 days