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CalcivoTools

JWT Decoder : Inspect JSON Web Token Header & Claims Online

The Calcivo JWT Decoder unpacks JSON Web Tokens (RFC 7519) into human-readable JSON header and payload claims. It automatically checks expiration timestamps and displays token properties completely in your browser without transmitting sensitive tokens to remote endpoints.

Interactive Calculator

100% Client-Side Engine
Security Notice — Decode Only: This tool parses and reads JWT header and payload claims entirely inside your browser. It does NOT verify the cryptographic signature against a secret key. A successfully decoded token is NOT proof that the token is valid, trusted, or untampered.
179 chars
Decode Status
Decoded Successfully
Expiration (exp)
Active (Not Expired)
Algorithm
HS256
Token Timestamps (UTC)
Issued At (iat): Tue, 14 Nov 2023 22:13:20 GMT
Expires At (exp): Sun, 17 Mar 2030 17:46:40 GMT
Header (JOSE)
{
  "alg": "HS256",
  "typ": "JWT"
}
Payload (Claims)
{
  "sub": "1234567890",
  "name": "Developer",
  "iat": 1700000000,
  "exp": 1900000000
}
Signature Bytes (Base64URL)
4vT3j4qf13jU7Bq2nK1P3v6r2k9q8z7x6c5v4b3n2m1
RFC 7519 Compliant JSON Web Token DecoderZero Network Transmission

Step-by-Step Examples

Inspecting Bearer Authorization Token

Checking user ID (sub), issuer (iss), and expiry timestamp on an OAuth2 token.

Inputs: Token Format: Header.Payload.Signature
Result: Decoded JSON Header (alg: HS256) and Payload with human-readable timestamps.

Converts epoch integers in "iat" and "exp" claims into human UTC calendar dates.

How to Use This Tool

  1. Paste your encoded JSON Web Token into the input area.
  2. The parser splits the token into Header, Payload, and Signature components.
  3. Review parsed JOSE headers, expiration status, and payload claims.
  4. Copy the formatted JSON payloads directly to your clipboard.

Frequently Asked Questions

No. This is strictly a client-side DECODER, not a signature validator. It does not verify signatures against private keys. A decoded token is not proof that the token has not been tampered with.

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