JWT Header Viewer Guide

What this guide covers

Use this JWT Header Viewer to decode only the first part of a JWT token and display the header as readable JSON. It is useful when you only need to inspect header values such as alg, typ, kid, cty, and other metadata without parsing the full payload.

This guide explains when to use JWT Header Viewer, how to get a cleaner result, and which mistakes to avoid before moving on to related tools or the main tool page.

Why use JWT Header Viewer

• Inspect JWT header metadata quickly
• Check alg, typ, kid, and related fields without payload noise
• Use a narrower view when troubleshooting tokens
• Avoid scanning the whole token when only the header matters
• Decode the header directly in the browser

How to use JWT Header Viewer

1. Paste the full JWT token into the input box
2. Click Run Tool to decode the header segment
3. Review the JSON output for header values
4. Copy the result for debugging or comparison
5. Use JWT Decoder or JWT Parser if you also need the payload

Best use cases

• Checking JWT alg and kid values
• Reviewing signing metadata quickly
• Comparing headers across tokens
• Inspecting token type and custom header fields
• Troubleshooting JWT setup without payload noise

Common mistakes