HTTP Header Viewer

The HTTP Header Viewer is a client-side tool that parses raw HTTP request or response headers into a structured, readable format. Paste the raw header text (including the status line if present, e.g., HTTP/1.1 200 OK), and the tool splits each line at the first colon, extracts the header name and value, and displays them as a JSON object. If the first line is an HTTP status line (starting with HTTP/), it is extracted separately and displayed at the top. The output shows the total header count in the info bar. This is essential for debugging HTTP communication — when you copy headers from curl output, browser DevTools Network tab, or server logs, they arrive as raw text that is difficult to scan. The parsed JSON format makes it trivial to find specific headers, verify that required headers are present, and check header values.

HTTP headers are the metadata layer of web communication, and debugging header-related issues is a daily task for web developers. When a CORS error occurs, you need to check Access-Control-Allow-Origin. When caching behaves unexpectedly, you need to verify Cache-Control and ETag. When authentication fails, you need to inspect Authorization and Set-Cookie. The HTTP Header Viewer transforms raw header dumps into a scannable, searchable format, making these checks instant instead of requiring manual line-by-line reading of dense header text.

This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.

Does it handle multi-line header values?

<p>HTTP headers are single-line by spec. If you paste multi-line content, only the first line of each header is captured. Folded headers (obsolete in HTTP/1.1) are not supported.</p>

Can I use this for gRPC headers?

<p>gRPC uses HTTP/2 headers, which follow the same name: value format. The tool can parse them, but gRPC-specific metadata may require additional context.</p>

What about cookie headers?

<p>Cookie and Set-Cookie headers are displayed as their raw values. For structured cookie parsing, use a dedicated cookie parser tool.</p>

Can I view request headers from curl output?

<p>Yes. Copy the headers from curl -v or curl -i output and paste them. The tool parses the raw header text regardless of its source — curl, browser DevTools, or server logs.</p>

What about headers with colons in the value?

<p>The tool splits at the first colon only, which correctly handles header values that contain colons (e.g., Authorization: Bearer token:with:colons).</p>

Does it validate header names?

<p>No. The tool parses headers as-is without validating that names follow HTTP header naming conventions. Invalid header names are displayed as-is for inspection.</p>

Can I view gRPC response headers?

<p>gRPC uses HTTP/2 with binary framing, but the metadata (headers) follow the same name:value text format. Copy the headers from your gRPC client logs and paste them.</p>

How does it handle duplicate header names?

<p>If a header name appears multiple times (e.g., Set-Cookie), the last value overwrites earlier ones in the JSON output. For headers that legitimately repeat, you would need to check the raw text.</p>