JWT Parser
Decode and analyze JSON Web Tokens instantly
JWT Token Input
All parsing happens in your browser - no data is sent to any server
Token Structure
Decoded JWT
Header
Paste a JWT token to see decoded header...
Payload
Paste a JWT token to see decoded payload...
Claims Explanation
When to Use JWT Parser
Debug Authentication Issues
Quickly decode JWT tokens to troubleshoot authentication problems in your application. Verify token claims, check expiration times, and ensure correct data is being transmitted.
API Development
During API development, parse JWT tokens to validate that your authentication service is issuing tokens with correct structure, claims, and algorithms.
Security Auditing
Security professionals can decode JWTs to audit token contents, verify proper security practices, and identify potential vulnerabilities in token implementation.
Token Expiration Check
Verify when a JWT token expires by decoding the exp claim. Our tool converts Unix timestamps to readable dates, making it easy to check token validity periods.
Learning & Education
Students and developers learning about JWT can use this tool to understand token structure, see how header and payload are encoded, and explore different JWT implementations.
Integration Testing
Test third-party API integrations by decoding tokens received from external services. Verify that incoming JWTs contain expected claims and data structures.
Frequently Asked Questions
What is a JWT token?
JWT (JSON Web Token) is an open standard (RFC 7519) for securely transmitting information between parties as a JSON object. A JWT consists of three parts: Header (token type and algorithm), Payload (claims and data), and Signature (verification code). JWTs are commonly used for authentication and information exchange in web applications and APIs.
How do I use this JWT parser tool?
Using our JWT parser is simple: 1) Paste your JWT token into the input field, 2) The tool automatically decodes and displays the Header and Payload sections, 3) View decoded claims like issuer, subject, expiration time, and custom data, 4) Check the timestamp conversions for iat, exp, and nbf fields. All parsing happens in your browser for maximum security.
Is it safe to decode JWT tokens with this tool?
Yes, our JWT parser is completely safe. All token decoding happens entirely in your browser using client-side JavaScript - no data is sent to any server or stored anywhere. Your JWT tokens never leave your device. However, remember that decoding a JWT only reads its contents; it doesn't validate the signature or verify authenticity without the secret key.
What information can I see in a decoded JWT?
When you decode a JWT, you can see: Header (algorithm type like HS256 or RS256, token type), Payload (standard claims like iss, sub, aud, exp, nbf, iat, jti, plus any custom claims added by the issuer), and the Signature portion. Our tool also converts Unix timestamps to human-readable dates for easier understanding of token validity periods.
Can this tool validate or verify JWT signatures?
This tool focuses on decoding and displaying JWT contents. It parses the Header and Payload to show you what data is stored in the token. However, it does not validate signatures because that requires the secret key or public key used to sign the token. For signature verification, you would need server-side validation with the appropriate key.
Why would I need to parse a JWT token?
You might need to parse JWT tokens for various reasons: debugging authentication issues in your application, inspecting token claims and expiration times, verifying that your API is issuing correct tokens, understanding what data is being transmitted, troubleshooting access control problems, or learning how JWTs work. Developers, security professionals, and API users frequently need to decode JWTs during development and testing.
What are the common JWT algorithms?
Common JWT signing algorithms include: HS256 (HMAC with SHA-256, symmetric key), HS384 (HMAC with SHA-384), HS512 (HMAC with SHA-512), RS256 (RSA with SHA-256, asymmetric), RS384 (RSA with SHA-384), RS512 (RSA with SHA-512), ES256 (ECDSA with SHA-256), ES384 (ECDSA with SHA-384), and ES512 (ECDSA with SHA-512). The algorithm is specified in the JWT header.
What do the JWT claim abbreviations mean?
Standard JWT claims include: iss (Issuer - who created the token), sub (Subject - who the token is about), aud (Audience - who should accept the token), exp (Expiration Time - when token expires), nbf (Not Before - when token becomes valid), iat (Issued At - when token was created), jti (JWT ID - unique identifier). These are registered claims defined in the JWT specification, but tokens can also include custom claims with any name.
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