Paste your JWT token
Copy and paste your JSON Web Token into the JWT decoder input. The tool automatically detects the three JWT segments (header, payload, signature) separated by dots and prepares them for decoding.
JWT Decoder
Decode any JSON Web Token (JWT) to inspect its header, payload, and signature information. Paste a JWT string and instantly see the decoded header and payload as formatted JSON. Perfect for debugging authentication flows, verifying token contents, and learning JWT structure.
Workspace
Use the tool below. Your inputs stay local when the tool supports browser-only processing.
Last reviewed: · Testing methodology
Workflow
How to use the JWT Decoder
View decoded header and payload
The JWT decoder instantly shows the decoded header (token type and signing algorithm) and payload (claims like subject, issuer, and expiration) as formatted, readable JSON objects for easy inspection.
Copy decoded data
Use the copy buttons to grab the decoded header or payload JSON. The JWT decoder is perfect for debugging authentication issues, verifying token contents during development, and learning about JWT structure.
Decode JWT Tokens Safely
The JWT decoder reads the header and payload locally in your browser. This helps developers inspect authentication claims without sending tokens to a remote debugging service.
What the Tool Does Not Do
Decoding a JWT is not the same as verifying trust. This tool displays token content for debugging, but production verification must still check signatures, issuers, audiences, and expiration rules.
Developer Use Cases
Use the decoder while debugging OAuth, OpenID Connect, API sessions, test environments, and claim mappings. Avoid pasting live production secrets unless you understand the risk.
How this tool works
The component splits the token, converts Base64URL segments into text, and parses the header and payload JSON. It does not use a signing key and therefore cannot authenticate the token.
- Engine: Base64URL decoding plus JSON parsing
- Supported input: three-part JSON Web Tokens
- Output: decoded header, decoded payload, human-readable time claims
- Input
- A JWT whose payload contains {"sub":"123"}
- Output
- Decoded payload showing sub = 123; signature status remains unverified
Limits, edge cases, and troubleshooting
Use only for inspection and debugging. Treat pasted production tokens as secrets and never authorize a request based on decoded claims alone.
- The token must contain decodable Base64URL JSON segments.
- Decoding does not verify the signature, issuer, audience, revocation state, or trustworthiness of any claim.
When to use another workflow
Use your authentication library or jwt.io with the correct algorithm and trusted key material when signature and claim validation are required.
| Option | Best for | Trade-off |
|---|---|---|
| This browser tool | Quick, private, one-off work | Limited by browser memory and the documented feature set |
| Desktop or command-line tool | Batch jobs and repeatable automation | Requires installation and setup |
Verification
Reviewed by the Free Online Tools Nest Team on 2026-08-26. The interface, output path, and documented limitations were checked against the current implementation. See our testing methodology for the review process.
Read the testing methodologyJWT Decoder — Frequently Asked Questions
Is the JWT decoder safe to use with production tokens?
The decoder processes the pasted token locally and does not send it to our processing server. Tokens are credentials and can still be exposed through clipboard history, extensions, screenshots, or device compromise, so use an expired or redacted sample instead of an active production token.
Does the JWT decoder verify token signatures?
The JWT decoder decodes and displays the header and payload but does not verify cryptographic signatures. For signature verification, you need the secret key or public key used to sign the token, which is a server-side operation.