JWT Decoder
Decode any JWT instantly. View header, payload, and claims with expiry status — 100% in your browser.
JWT Decoder splits a JSON Web Token into its three Base64URL-encoded parts — header, payload, and signature — and shows decoded JSON for each. Includes colour-coded expiry badges (valid, expiring within 24h, expired) and claim summaries. Everything runs in your browser; tokens never reach a server. FreeToolHub.
Header
Payload
Signature
The signature cannot be verified without the secret key. It is shown as-is for reference.
Claims Summary
Frequently Asked Questions
What is a JWT?
A JWT (JSON Web Token) is a compact, URL-safe token used to securely transmit information between two parties. It consists of three Base64URL-encoded parts — header, payload, and signature — joined by dots.
Is it safe to paste my JWT here?
This tool runs entirely in your browser. No data is sent to any server — your token never leaves your device.
What are the three parts of a JWT?
A JWT has three parts: the Header (token type and signing algorithm), the Payload (claims and data), and the Signature (used to verify authenticity).
Why can't I verify the signature?
Signature verification requires the secret key or public key used to sign the token. This tool is decode-only and does not perform verification.
What does the exp claim mean?
The exp claim is a Unix timestamp representing when the token expires. This tool highlights tokens that are expired or expiring soon.
What JWT algorithms are supported?
This tool decodes any JWT regardless of algorithm — HS256, RS256, ES256, and more. The algorithm is shown in the header panel.