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JWT Decoder

Read the header and payload of a three-part JWT locally.

Read the header and payload of a three-part JWT locally.

Up to 16 KiB. Three base64url segments only; encrypted five-part JWE is unsupported. Decode header/payload with strict UTF-8 and JSON checks. This does not verify signatures, issuer, audience or authenticity. Dates are displayed as UTC; never treat a decoded token as trusted.

How to use

JWT Decoder

Read the header and payload of a three-part JWT locally.

Step by step

  1. Choose a supported input or load the example, then review the original.
  2. Read the header and payload of a three-part JWT locally. Start with the displayed settings, change only the options needed for your output and compare the result with your source.
  3. Run the task, review the actual result and copy or download a checked copy.

Choosing the settings

OptionWhat changes
OptionsRead the header and payload of a three-part JWT locally. Start with the displayed settings, change only the options needed for your output and compare the result with your source.
LimitsUp to 16 KiB. Three base64url segments only; encrypted five-part JWE is unsupported. Decode header/payload with strict UTF-8 and JSON checks. This does not verify signatures, issuer, audience or authenticity. Dates are displayed as UTC; never treat a decoded token as trusted.

Example and expected result

A synthetic payload {"sub":"demo","iat":0} displays sub = demo and iat = 1970-01-01 00:00:00 UTC. The signature stays unverified.

If it is not working

  • Expected 3 JWT segments. This may be encrypted JWE or malformed text; no verification was performed.

Formats and limits

Up to 16 KiB. Three base64url segments only; encrypted five-part JWE is unsupported. Decode header/payload with strict UTF-8 and JSON checks. This does not verify signatures, issuer, audience or authenticity. Dates are displayed as UTC; never treat a decoded token as trusted.

FAQ

What does this tool do?

Read the header and payload of a three-part JWT locally.

Which setting should I choose?

Read the header and payload of a three-part JWT locally. Start with the displayed settings, change only the options needed for your output and compare the result with your source.

What are the limits?

Up to 16 KiB. Three base64url segments only; encrypted five-part JWE is unsupported. Decode header/payload with strict UTF-8 and JSON checks. This does not verify signatures, issuer, audience or authenticity. Dates are displayed as UTC; never treat a decoded token as trusted.

Why did processing fail?

Expected 3 JWT segments. This may be encrypted JWE or malformed text; no verification was performed.

Is my input uploaded or saved?

No. Processing runs on your device. Inputs and results stay in this page’s memory until you clear it or leave. They are not uploaded, logged or stored by ToolRobin. Copying places the result on your device’s clipboard.

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