A JSON Web Token (JWT) is a compact, URL-safe string used to represent claims between two parties. It consists of three Base64URL-encoded parts separated by dots: header.payload.signature.

Is the signature verified?

Signature verification requires the secret or public key, which is never available client-side. This tool only decodes the header and payload, it does not validate the token.

Is my token safe to paste here?

Yes. All decoding runs in your browser using JavaScript. Our servers are not involved at any point. However, treat tokens as sensitive credentials and avoid pasting production tokens in shared environments.

What is the exp claim?

The exp (expiration) claim is a Unix timestamp indicating when the token expires. This tool reads that value and shows whether the token is still valid or has expired.

JWT decoder

Paste a JSON Web Token to decode and inspect its header and payload. The expiry time is displayed automatically if the payload contains an exp claim. All decoding runs locally in your browser.

JWT token

⚠ Signature not verified, client-side only

VIEW

Runs entirely in your browser

How it works

A JWT consists of three Base64URL-encoded parts separated by dots. The tool splits the token, fixes URL-safe base64 encoding (replacing - with + and _ with /), pads to a multiple of 4 characters, then decodes with atob() and parses with JSON.parse(). All of this runs in your browser. Our servers are not involved.

Processing runs in your browser

Your JWT is decoded entirely in your browser. Our servers are not involved at any point. Treat tokens as sensitive credentials and avoid pasting production tokens in shared or public environments. You can check this yourselfin your browser's DevTools Network tab.

Technical specification

JSON Web Token (JWT) is defined in RFC 7519 (IETF, 2015). A JWT consists of three Base64url-encoded sections separated by .: header, payload, and signature. Base64url encoding is defined in RFC 4648 §5, which substitutes + with - and / with _ and omits padding, making it safe for use in URLs without percent-encoding. Signed JWTs (JWS) are specified separately in RFC 7515.

Structure: header.payload.signature (3 Base64url parts)
Standards: RFC 7519 (JWT), RFC 7515 (JWS), RFC 4648 (Base64url)
Header claims: alg (algorithm), typ (token type)
Common payload claims: sub, iss, exp, iat, aud

Related operations

To inspect the raw Base64 segments of a token, try Base64. For verifying the signing input by hash, use the hash generator. To pretty-print decoded payloads, see the JSON formatter.

Frequently asked questions

What is a JWT?: A JSON Web Token (JWT) is a compact, URL-safe string used to represent claims between two parties. It consists of three Base64URL-encoded parts separated by dots: header.payload.signature.
Is the signature verified?: Signature verification requires the secret or public key, which is never available client-side. This tool only decodes the header and payload, it does not validate the token.
Is my token safe to paste here?: Yes. All decoding runs in your browser using JavaScript. Our servers are not involved at any point. However, treat tokens as sensitive credentials and avoid pasting production tokens in shared environments.
What is the exp claim?: The exp (expiration) claim is a Unix timestamp indicating when the token expires. This tool reads that value and shows whether the token is still valid or has expired.