JWT Header Viewer
Inspect the header section of a JWT token.
About JWT Header Viewer
JWT Header Viewer focuses on the header portion of a JWT, showing the signing algorithm (alg), token type (typ), and any other header claims in a readable format. This is useful for quickly confirming whether a token uses HS256, RS256, ES256, or another algorithm, which matters when configuring your auth server or debugging signature verification failures.
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Frequently Asked Questions
Is JWT Header Viewer free?
Yes, completely free. No signup, no account, no usage limits. Use it as much as you need.
Is my data secure?
All processing happens directly in your browser using JavaScript. Your data is never sent to any server, stored, or shared. It stays entirely on your device.
What information is typically in the JWT header?
The header usually contains the algorithm (alg) and token type (typ). Some tokens also include a key ID (kid) that tells the server which key to use for verification.
Why would I use the Header Viewer instead of the full JWT Decoder?
The Header Viewer is focused on the header only, which is useful when you specifically want to check the algorithm or key ID without seeing the full payload.