HTTP Headers Viewer

Fetches the response headers of any URL by performing a browser GET request with redirect: follow, then lists every header name/value pair returned. The HTTP status code is shown as a colored badge (green for 2xx, yellow for 3xx, red for 4xx/5xx) and all headers can be copied as plain text at once.

1. Type a URL into the input. If it does not start with http, https:// is added for you. 2. Click Lookup (or press Enter). The status badge and header list appear below. 3. Use Copy all to copy every header in Name: Value format to the clipboard.

The list comes directly from the Fetch API's response.headers iterator. Because this is a browser fetch, only CORS-safelisted and explicitly exposed headers are visible for cross-origin responses; restricted headers such as Set-Cookie will not appear unless the server sends Access-Control-Expose-Headers for them. For same-origin or CORS-enabled targets, the full exposed set is shown.