Before you start
- Use only data you are entitled to inspect, and avoid pasting live credentials into screenshots or shared notes.
- Decide where the final value will be stored before generating or copying it.
MV ToolsJWT tool
JWT Decoder Online
Decode the header and payload of a JSON Web Token directly in your browser without uploading the token.
Decode JWT claims as untrusted display data
Inspect a token’s header and payload locally, but make authorization decisions only after signature and claim validation in the application that owns the token.
- The tool parses three JWT segments and displays header, payload, signature text, and common time claims.
- It does not verify the signature, issuer, audience, intended algorithm, or permission to use the token.
- An “active” expiry display only compares exp with the current clock; it is not a trust decision.
Decoding, copying, and display stay in the browser. Treat real access tokens as sensitive and use a redacted or test token whenever possible.
How to Generate, Check, and Inspect Security Data LocallyTreat generated and decoded values as sensitive
Check the result
- Confirm the algorithm, character set, claims, or digest matches the system that will consume it.
- Verify expiry and issuer details for tokens, and compare hashes only from the exact same source bytes.
Know the limit: Decoding, generating, or hashing does not authenticate a token, recover a password, or replace a security review.
JWT Decoder Online
Decode JSON Web Token header and payload claims locally in your browser for API debugging, authentication testing, and token inspection.
What This Tool Does
This browser-based JWT decoder splits a token into header, payload, and signature parts, decodes the Base64URL JSON, formats the header and payload, and highlights common claims such as alg, typ, iss, sub, aud, iat, nbf, and exp.
Common Use Cases
- Inspecting JWT payload claims from an API response or authentication flow
- Checking exp, iat, and nbf timestamps while debugging token lifetime issues
- Reading JWT header values such as alg, typ, and kid without uploading the token
How Data Is Handled
JWT decoding runs entirely in your browser. The token is not uploaded to the backend, and the signature is displayed but not verified.
FAQ
Does this verify the JWT signature?
No. This first version decodes and displays the token only. It does not verify whether the signature is valid.
Is my JWT sent to the server?
No. Header and payload decoding run locally in your browser.
Can I decode expired tokens?
Yes. The tool can decode expired tokens and shows whether an exp claim is already in the past.