How Client-Side JWT Decoding Works
JWT Token Decoder runs entirely in your browser with JavaScript. There is no sign-up, and whatever you type or open here is processed on your device instead of being sent to a server.
Inspect JSON Web Tokens Without Sending Secrets to Servers
JSON Web Tokens frequently contain sensitive authentication claims, user IDs, email addresses, and organizational scopes. Pasting production auth tokens into public web debuggers risks leaking credentials. This decoder parses Base64URL-encoded headers and payloads 100% on-device in browser memory, never sending your tokens to any remote server.
Automatic Bearer Stripping and Expiry Conversion
You can paste raw tokens directly or include standard Bearer prefixes from authorization headers. The decoder automatically extracts the token parts and shows the iat and exp claims as readable UTC dates, marking the token ACTIVE or EXPIRED.
Understanding Token Structure: Header, Payload & Signature
A standard JWT consists of three parts separated by dots: the algorithm header, the claim payload, and the signature hash. This utility decodes the first two parts so you can read the claims and check the expiry time; the signature is not checked, so decoding alone does not prove a token is genuine. JWT payloads are Base64URL-encoded, not encrypted, so anyone who has a token can read its claims; never put passwords or other secrets in a JWT.
Why processing in your browser matters
Many online tools upload your files or text to a server to process them. This one does the work on your computer or phone, so your data is not sent to us or stored anywhere else. That lowers the risk when you work with confidential material, although you should still follow your organisation's own rules. Read how this works in our Privacy Policy.
- No uploads: files are opened and saved on your device, so there is no upload or download wait.
- No account: nothing to sign up for or install.
- Free to use: no subscriptions or paywalls.