JWT (JSON Web Token) Header & Payload Inspector
Safely decode and inspect Base64Url encoded JWT headers and claims payloads client side with syntax highlighting, expiration countdowns, and zero token…
How to Use the JWT (JSON Web Token) Header & Payload Inspector
- 1 Paste your raw JSON Web Token (`header.payload.signature`) into the editor.
- 2 Inspect parsed JSON tabs: Header (Algorithm & Token Type) and Payload (Claims, User ID, Roles).
- 3 Review automated security checks: Token Expiration Date (`exp`), Issued-At (`iat`), and Not-Before (`nbf`).
- 4 Copy formatted JSON with one click.
Methodology & Algorithmic Standards
Splits the token by period separators, decodes RFC 7519 Base64Url strings locally using `atob()` with safe UTF8 replacement, and parses JSON structures. Never transmits tokens over the network.
Frequently Asked Questions
Is it safe to paste confidential authentication JWTs here? ▼
Yes! All token decoding executes 100% locally in your browser memory via native JavaScript. No network requests are made, ensuring your secrets and session tokens never leave your machine.
Does this tool verify cryptographic token signatures? ▼
No. Signature verification requires knowing your backend server's private key or HMAC secret. To maintain zero-knowledge client side security, this tool inspects decoded header and payload claims only.
How does it display human readable expiration dates? ▼
Standard JWT `exp` and `iat` claims represent Unix timestamps in seconds. The tool multiplies by 1,000 and displays localized calendar dates and remaining active hours.
Explore Related Developer Tools
JSON Formatter, Minifier & Syntax Linter
Fast, client side JSON beautifier, minifier, and error linter. Safely formats code with 2 space or 4 space indentation and pinpoints exact syntax error line numbers.
Base64 Text & String Encoder / Decoder
Safely encode and decode UTF8 text and Unicode characters to and from Base64 with instant copy, byte telemetry, and zero server logging.
URL Slug & Query Parameter Parser
Deconstruct any web URL into protocol, host, port, path, and an interactive editable table of query parameters with live re assembly and copy.