JWT Decoder

• 100% Free

  Core tools stay free with no paywall to unlock basics.

• No Registration Required

  Open a tool and start immediately - no account needed.

• Privacy First

  We avoid unnecessary collection and keep processing local when possible.

• Browser Processing

  Most tools run in your browser so your input never needs a server round-trip.

• Fast & Secure

  HTTPS everywhere with instant, client-side results for everyday tasks.

• Mobile Friendly

  Layouts and controls are built for phones, tablets, and desktops.

• Updated Regularly

  Tools and content are improved continuously as the platform grows.

Key Features

• Header & payload breakdown

  View the decoded JWT header and payload as formatted, readable JSON instantly, without writing any code.

• Expiration insights

  See issued-at (iat) and expiration (exp) timestamps converted to readable dates, plus time remaining or elapsed.

• Clear decode-vs-verify distinction

  The tool only reads the header and payload - it never claims to validate the signature, so you always know what was and was not checked.

• Browser-only, no upload

  Tokens are decoded locally in JavaScript. Nothing is sent to a server, even for expired or malformed tokens.

How to Use

1. 1

   Paste your JWT

   Copy a token from your app, an API response, browser dev tools, or an authentication log.

2. 2

   Review the decoded JSON

   Inspect the header’s algorithm and type fields, and the payload’s claims, in readable formatted JSON.

3. 3

   Check expiration and issued time

   Confirm the iat and exp claims and see whether the token is currently valid based on time alone.

4. 4

   Verify separately if trust matters

   Treat decoding as inspection only - validate the signature on a trusted backend before trusting any claim.

Use Cases

• Debugging authentication flows

  Inspect access and ID tokens issued by an OAuth or OpenID Connect provider to confirm expected claims are present.

• Reviewing API access tokens

  Check the subject, audience, scope, or role claims inside a bearer token during backend or integration development.

• Diagnosing expired-session issues

  Compare a token’s exp claim against the current time to confirm whether "unauthorized" errors are caused by expiry.

• Learning JWT structure

  Explore how a real-world JWT is assembled from header, payload, and signature segments for training or documentation purposes.

Examples

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

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

header.eyJzdWIiOiJhYmMiLCJleHAiOjE3MDAwMDAwMDB9.signature

{
  "sub": "abc",
  "exp": 1700000000
}
Expired: Yes (time remaining is negative)

Benefits

• ✓Debug authentication and authorization flows faster
• ✓Inspect claims without writing backend decoding code
• ✓Check token expiry and issued time during development
• ✓Learn JWT structure with real, readable examples
• ✓No account, install, or upload required to inspect a token

Best Practices

• Use sample or staging tokens rather than pasting live production secrets into any online tool.
• Remember that decoding does not prove a token is trustworthy - only signature verification does that.
• Compare the exp claim against your server’s clock if a token appears expired unexpectedly.
• Check the alg field in the header, and never trust an "alg: none" token from an untrusted source.

Common Mistakes

• Treating a decoded JWT as proof of authenticity without ever verifying the cryptographic signature.
• Pasting production access or refresh tokens into public demos, shared screens, or chat messages.
• Assuming the payload is encrypted - JWT payloads are only base64url-encoded and readable by anyone with the token.

Privacy Notice

All decoding runs locally in your browser using JavaScript. JWTs are never uploaded to ToolMint servers or any third party, even if the token is invalid.

About This Tool

Frequently Asked Questions

Related Tools

• Developer

  JSON Formatter

  Format and validate JSON instantly.

  Privacy firstBrowser
• Security

  Password Generator

  Generate secure random passwords instantly in your browser.

  Privacy firstBrowser
• Text

  Case Converter

  Convert text between common letter cases.

  Privacy firstBrowser

Suggested Articles

• Understanding JWT Tokens: Inspect Safely, Trust Carefully

  What JSON Web Tokens are, how header/payload/signature fit together, how to decode them safely, and the security caveats developers still miss.

• How to Format and Validate JSON Without Losing an Afternoon

  Common JSON syntax errors, when to pretty-print or minify, how validation catches bad payloads early, and practical tips for API debugging.

• Why Browser-Based Tools Are Often More Private

  How client-side processing keeps files on your device, when servers are still necessary, and how ToolMint approaches privacy for everyday utilities.

Share this tool