Developer Tools
Find clear answers to common questions about JWT Header Viewer, including usage, output, and common issues.
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.
JWT Header Viewer is built for development, debugging, formatting, and quick technical checks directly in the browser.
It decodes and shows only the header part of a JWT token.
Common fields include alg, typ, kid, and sometimes cty.
No. It only decodes the header.
JWT Header Viewer focuses only on the first JWT segment, while JWT Decoder shows the broader token content.
Use it when you only need header metadata and do not want payload details.
JWT Header Viewer is built for development, debugging, formatting, and quick technical checks directly in the browser.
Start by checking the input format, removing accidental spaces or unsupported characters, and comparing your input against the example pattern on the page.
Fix: Paste the full JWT token with header, payload, and signature sections.
Fix: Use JWT Decoder or JWT Parser if you need the payload.
Fix: Check whether the token was copied fully and is actually a JWT.
If you want to see realistic input and output patterns, open the examples page. If you want step-by-step usage guidance, open the guide page.
Open the main JWT Header Viewer page to test your own input and generate a live result.