JWT Decoder
Decode and inspect JSON Web Tokens without sending data to a server.
Why use this solution
- Decode JWT tokens instantly without exposing sensitive key strings to external logging
- Format and syntax highlight the decoded header and payload JSON structures
- Extract important metadata claims such as expiration time, issuer, and audience
Who uses this
- Fullstack developers troubleshooting authentication token claims and expiration times
- Security researchers auditing token structures for compliance and validation
- DevOps engineers verifying ID tokens returned from OAuth identity providers
Configure inputs and click Run
How It Works & Educational Guide
How Nexifr's JWT Decoder handles your data securely in the browser — covering supported formats, encoding standards, and practical developer workflows.
01How JSON Web Tokens (JWT) Work
JWTs securely transmit information between parties as a JSON object. They consist of three distinct parts separated by dots: • Header: Specifies the token type and cryptographic signing algorithm (e.g. HS256, RS256). • Payload: Contains the claims or statements about the user entity and metadata. • Signature: Verifies that the sender is authentic and the token was not altered.
02Never Decode JWTs on External Servers
Since JWTs contain user authentication claims, roles, and user IDs, pasting them into server-based web tools leaks your session details. Nexifr decodes JWT blocks 100% locally in your browser context using Base64 URL decoding, keeping your credentials secure.
03Validating JWT Expiry and Claims
Our decoder parses claim keys such as `iat` (issued at), `exp` (expiration timestamp), and `sub` (subject), translating timestamps to readable local times to check token lifetimes.
Frequently Asked Questions
Is my JWT sent to a server?
No. Decoding is done entirely in your browser.
Can I verify JWT signatures?
We decode the payload and header but do not verify signatures in-browser.