JWT (JSON Web Token) is a compact, URL-safe token format used for authentication and information exchange. It consists of three parts: header (algorithm and token type), payload (claims and data), and signature (for verification). Tokens are Base64URL encoded and separated by dots.

Does this tool verify the JWT signature?

No, this tool only decodes the JWT structure—it doesn't verify signatures. Signature verification requires the secret key or public key used to sign the token. This tool is for inspection and debugging only, not for security validation. Always verify signatures in production using proper JWT validation libraries.

Can I use this to validate tokens?

This tool can check token structure and expiration claims, but it cannot validate token authenticity (signature verification). For production use, always validate tokens server-side with proper signature verification. This tool is best for debugging and inspection purposes.

What information is in a JWT token?

JWT tokens contain a header (algorithm, token type) and a payload (claims like user ID, roles, expiration time, issuer, audience, etc.). Common claims include 'sub' (subject), 'exp' (expiration), 'iat' (issued at), 'iss' (issuer), and custom application-specific claims.

Is it safe to decode JWT tokens?

Decoding JWT tokens is safe for inspection—the header and payload are Base64URL encoded, not encrypted. However, never share tokens publicly as they may contain sensitive information. This tool processes tokens locally in your browser—tokens are never sent to any server. For security, always verify signatures before trusting token contents.

JWT Decoder - View Header & Payload Free

When to Use This Tool

Use this when:

You're debugging authentication issues and need to inspect JWT token contents
You're developing APIs and need to verify JWT token structure and claims
You want to check token expiration or validate token data before using it
You're troubleshooting authentication errors and need to see what's in the token
You're learning about JWTs and want to understand token structure
You need to extract user information or claims from a JWT token
You're testing API integrations and need to verify JWT token format

Don't use this if:

You need to verify JWT signature or validate token authenticity (this tool only decodes, doesn't verify signatures)
You require server-side token validation with secret keys (this tool is client-side only)
You need to create or sign JWT tokens (this tool only decodes existing tokens)
You want to modify or edit JWT token contents (this tool is read-only)
You need to validate tokens against specific public keys or certificates (use specialized JWT validation tools)

What is a JWT Decoder?

A JWT (JSON Web Token) decoder parses and displays the header, payload, and signature components of a JWT token in a readable, formatted view. Our decoder runs entirely in your browser — your tokens (which may contain sensitive authentication data) are never sent to any server.

JWT tokens are the standard for authentication and authorization in modern web applications, used in OAuth 2.0, OpenID Connect, API authentication, single sign-on systems, and microservice communication. Being able to quickly inspect token contents is essential for debugging authentication issues.

This tool is essential for front-end developers debugging login flows, back-end engineers verifying token claims and expiration, security auditors inspecting token contents for sensitive data exposure, API developers troubleshooting authorization failures, and DevOps engineers debugging identity provider configurations.

Compared to jwt.io (which processes tokens on their server and was found to have tracked token data in the past), using console.log with atob() (which requires manual parsing and doesn't handle URL-safe Base64), or building custom decode scripts, PureXio provides instant, private JWT decoding with formatted output.

The tool displays the header (algorithm, type), payload (all claims including iss, sub, exp, iat with human-readable timestamps), and signature status. It highlights expired tokens, shows the expiration time in human-readable format ('expires in 2 hours' or 'expired 3 days ago'), and validates the token structure.

Best for: decoding and inspecting JWT tokens safely. Header, payload, claims, expiration display. Critical for auth debugging. 100% private — tokens never leave your browser.

How to Decode JWT Tokens

Paste your JWT token into the input field. JWT tokens have three parts separated by dots (header.payload.signature). Token is decoded automatically as you paste

Tool decodes JWT automatically, showing header (algorithm, token type) and payload (claims, data, expiration). Review decoded information in formatted JSON

Review decoded information. Copy decoded JSON or inspect specific claims. Note: Signature is not verified—this tool only decodes structure, doesn't validate authenticity

Common Use Cases

Debug authentication issues by inspecting JWT token contents and claims

Verify token expiration before using in API requests or authentication

Extract user information (user ID, roles, permissions) from JWT payload

Check token structure and format when troubleshooting API integration issues

Learn JWT structure by decoding sample tokens and viewing header/payload

Validate token claims (issuer, audience, expiration) before processing

Inspect JWT tokens from authentication providers or third-party APIs

Features

Decode JWT tokens to view header and payload data in formatted JSON

Automatic decoding as you paste—no button click required

Shows token expiration status (expired, valid, or no expiration claim)

Displays header information (algorithm, token type) and payload claims

Formatted JSON output for easy reading and inspection

Copy decoded JSON to clipboard with one click

100% private—all processing happens in your browser

Limitations & Constraints

Does not verify JWT signature—only decodes token structure (signature verification requires secret keys)

Cannot validate token authenticity or integrity—use this for inspection only, not security validation

Does not support encrypted JWTs (JWE)—only decodes signed JWTs (JWS)

Expiration checking is informational only—doesn't prevent use of expired tokens

Cannot create, sign, or modify JWT tokens—read-only decoding functionality

Troubleshooting

Token decoding fails or shows error

Solution: Check that token is a valid JWT format (three parts separated by dots: header.payload.signature). Ensure token is complete and not truncated. JWT tokens are Base64URL encoded—invalid encoding causes errors. Try copying token again from source. Prevention: Ensure token is complete and in valid JWT format.

Decoded data looks wrong or corrupted

Solution: JWT payload is Base64URL encoded JSON. If decoded data looks wrong, the token may be malformed or corrupted. Check that you copied the complete token. Some tokens may have invalid JSON in payload—this will show as an error. Prevention: Copy complete tokens from reliable sources.

Token shows as expired but should be valid

Solution: Expiration is based on 'exp' claim in token payload. Check the expiration timestamp (Unix epoch time). Token may be expired according to its own claims. Note: This tool only checks expiration claim—it doesn't verify if token is actually valid or if signature is correct. Prevention: Understand that expiration check is based on token claims only.

Need to verify token signature or authenticity

Solution: This tool only decodes tokens—it doesn't verify signatures. For signature verification, use JWT validation libraries or tools that support secret keys or public keys. Signature verification requires the secret key or public key used to sign the token. Prevention: Use specialized JWT validation tools for signature verification.

Token is encrypted (JWE) and can't be decoded

Solution: This tool only decodes signed JWTs (JWS), not encrypted JWTs (JWE). Encrypted tokens require decryption with the appropriate key. For encrypted tokens, use JWT libraries that support JWE decryption. Prevention: Understand that this tool works with signed tokens only, not encrypted tokens.