JWT Decoder
Decode JSON Web Token headers and payloads locally in your browser. Inspect claims, expiration timestamps, issuers, audiences, and custom fields while keeping token contents on your device.
Privacy & Security
All files are processed locally in your browser. Your data never leaves your device and is not uploaded to any server. We do not store, collect, or have access to your files.
How It Works
- 1
Paste a JWT into the input field
- 2
The tool decodes the Base64URL header and payload sections
- 3
Header and payload JSON appear in separate readable panels
- 4
Copy either decoded section for debugging or documentation
Use Cases
Inspect auth token claims during API development
Check token issuer, audience, subject, and expiration fields
Debug login flows and authorization middleware
Review custom JWT payload data during QA
Format JWT header and payload JSON for sharing with teammates
Frequently Asked Questions
Does this verify JWT signatures?
No. This tool only decodes the header and payload. It does not verify signatures or prove that a token is trustworthy.
Are tokens uploaded to AppUo?
No. Decoding happens entirely in your browser.
Can I paste production tokens?
Avoid sharing production tokens with anyone. This tool processes locally, but you should still treat JWTs as sensitive credentials.
Why is my token invalid?
A JWT should contain dot-separated Base64URL sections. Invalid padding, malformed JSON, or missing sections can prevent decoding.
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