TL;DR
A blogger running a site on Cloudflare Pages added the X-Clacks-Overhead HTTP response header as a tribute to author Sir Terry Pratchett. The header is injected via a plain-text _headers file and does not change performance or functionality.
What happened
The author of a personal blog reported adding an X-Clacks-Overhead HTTP response header to every request served by their site, hosted on Cloudflare Pages. The header is a reference to Terry Pratchett’s novel Going Postal and the fictional Clacks messaging system; its value is the traditional tribute string "GNU Terry Pratchett." On Cloudflare Pages this was implemented by placing a plain-text _headers file in the website’s root with a rule that applies the header to all paths (/*). The site operator notes the header has no functional effect on content delivery, caching, or site performance; it simply appears in response headers for static assets and HTML. They also shared simple ways to verify the header, such as using the browser developer tools Network tab or running curl -I against the site URL.
Why it matters
- It shows how custom HTTP headers can be used as small cultural or memorial gestures on the web.
- Cloudflare Pages supports injecting response headers through a root _headers file, illustrating a simple configuration mechanism for static sites.
- The addition demonstrates that non-functional metadata can be widely distributed without impacting performance or behavior.
- This is an example of how developers can personalize infrastructure-level responses without changing application code.
Key facts
- The blog is served on Cloudflare Pages.
- A plain-text _headers file placed in the root directory was used to add the header.
- The _headers file contains a rule scoped to all paths (/*) that sets the header.
- The header added is X-Clacks-Overhead with the value "GNU Terry Pratchett."
- The header references Terry Pratchett’s Going Postal novel and the Clacks system.
- The header is returned for static assets and HTML responses.
- The author says the header does not change performance or site functionality.
- Verification methods suggested: browser developer tools → Network tab, or curl -I https://hleb.dev.
- The blog post describing this was dated Dec 27, 2025 and published Jan 3, 2026 (UTC).
What to watch next
- Whether other site operators adopt X-Clacks-Overhead or similar headers as tributes — not confirmed in the source.
- Any platform-level guidance from hosting providers on use of non-functional response headers — not confirmed in the source.
Quick glossary
- HTTP response header: A key–value pair sent by a web server with an HTTP response that conveys metadata about the response or the server.
- Cloudflare Pages: A platform for deploying static sites that supports configuration through files placed in the site repository, including custom response headers.
- X-Clacks-Overhead: An informal HTTP header used by some sites as a tribute to Terry Pratchett; commonly set to the value "GNU Terry Pratchett."
- curl -I: A command-line option for curl that fetches and displays only the HTTP headers from a URL.
Reader FAQ
What does the X-Clacks-Overhead header do?
It serves as a tribute and carries the string "GNU Terry Pratchett"; it has no functional effect on the site according to the author.
How was the header added on this site?
By placing a plain-text _headers file in the site root on Cloudflare Pages with a rule that applies the header to all paths.
How can I check if a site returns this header?
Open your browser developer tools and inspect response headers in the Network tab, or run curl -I against the site URL.
Does the header affect performance or caching?
The author states it changes nothing about performance or functionality.
Will Cloudflare Pages add this header automatically for all sites?
not confirmed in the source
X-Clacks-Overhead Dec 27, 2025 I am a big fan of Sir Terry Pratchett. His books influenced my sense of humor and the way I look at things, far beyond just…
Sources
- X-Clacks-Overhead
- GNU Terry Pratchett – James Leighton
- X-Clacks-Overhead: GNU Terry Prachett – osgav
- Stopping Terry Pratchett sneaking into my HTTP headers
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