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Base64 Encoder / Decoder
Encode text to Base64 and decode Base64 back to readable text locally in your browser.
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JWT Decoder
Decode JWT header and payload claims locally in your browser without uploading tokens or verifying signatures.
Runs locally in your browser
JWT Decoder
Decode JWT header and payload claims for debugging. Signature verification is not performed.
How to use it
What this JWT Decoder is for
Use this JWT Decoder to inspect the header and payload of a JSON Web Token while debugging authentication flows, OAuth integrations, API requests, or local development test tokens.
The decoder runs in your browser. It does not upload the token, decoded claims, or copied output to a server.
Important security note
Decoding is not validation. A JWT payload is just base64url-encoded JSON until your backend verifies the signature and checks claims such as issuer, audience, expiration, not-before time, and scopes.
Do not treat a token as trusted because it can be decoded. Treat decoded output as inspection data only.
How to use it
Paste a JWT with three dot-separated segments, then click Decode JWT. The tool displays the decoded header, decoded payload, common claim summary, and whether a signature segment exists.
Use test tokens or redacted examples when possible. Real access tokens and ID tokens may contain sensitive user, tenant, or authorization data.
Related reading
Use the Unix Timestamp Converter when you need to inspect JWT iat, nbf, or exp values as UTC and local dates. Read JWT Claims Explained for common claims and validation mistakes, JWT vs Session Authentication for architecture tradeoffs, Access Token vs Refresh Token for token lifecycle decisions, and OAuth 2.0 vs OpenID Connect for access-token and ID-token boundaries. For the full sequence, browse the Authentication Learning Path.
For the broader security sequence, browse the Backend Security Learning Path.
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JWT Decoder questions
Does this JWT Decoder upload my token?
No. Decoding runs locally in your browser, and the tool does not send JWT input to a server.
Does this tool verify the JWT signature?
No. It decodes the header and payload only. A decoded token is not automatically trusted unless the signature, issuer, audience, and expiration are validated by your backend.
Is it safe to paste a production JWT here?
Avoid pasting real production tokens into any web tool unless you fully trust the environment. Prefer using test tokens or redacted examples.
What parts of a JWT does this show?
It shows the decoded header, decoded payload, common registered claims, and whether a signature segment is present.