Useful for
- Format, validate, encode, decode, inspect, or generate developer-friendly values.
- Troubleshoot copied snippets before adding them to a project.
- Prepare quick examples for documentation, testing, support, or debugging.
JWT Decoder
Decode the header, payload, and signature of a JSON Web Token without sending it to a server.
HEADER Algorithm & token type
PAYLOAD Claims & data
SIGNATURE Base64URL-encoded
Tool guide
How to use JWT Decoder
JWT Decoder gives you a focused way to handle one small task quickly. Decode the header, payload, and signature of a JWT token in your browser. It is free to use, requires no login, and is built for quick checks when you need a practical result.
Example
For example, use JWT Decoder while checking an API response, preparing a test value, inspecting a URL, or cleaning up code-adjacent text.
Good to know
Most developer utilities run in your browser. Avoid pasting secrets, API keys, passwords, or private production data into any online tool.
How it works
The JWT decoder splits a JSON Web Token into its three Base64URL-encoded parts and decodes the header and payload into readable JSON. It does not verify the signature cryptographically.
JWT = header.payload.signature. Each part is Base64URL encoded; the decoder reads the header and payload only.
Practical examples
- Inspect the algorithm and token type in the header.
- Read claims like sub, name, iat, and exp from the payload.
- Check if a token has expired by comparing the exp timestamp to the current time.
Common mistakes
- This tool decodes but does not verify the signature. Do not trust a decoded JWT without verifying it cryptographically.
- Never paste production access tokens or refresh tokens into any online tool. Use only test or example tokens.
Questions
Does this tool verify the JWT signature?
No. It only decodes the header and payload. Signature verification requires the secret or public key.
Is my token sent to a server?
No. All decoding happens in your browser. The token never leaves your device.