Glossary · HTTP, edge and rendering
cache-buster
A random query parameter appended to a URL so that the request misses every cache keyed on the URL and reaches the origin.
What cache-buster means
A random query parameter appended to a URL so that the request misses every cache keyed on the URL and reaches the origin. It is a measurement tool, not a fix: it shows what the origin serves now, and it says nothing about what the edge is still serving to everyone who asks for the bare URL.
What cache-buster can and cannot support
| It can support | It cannot support |
|---|---|
| A random query parameter appended to a URL so that the request misses every cache keyed on the URL and reaches the origin. | It is a measurement tool, not a fix: it shows what the origin serves now, and it says nothing about what the edge is still serving to everyone who asks for the bare URL. |
How CrawlCheck measures cache-buster
3 finding codes in the scanner read this. The share of all scans carrying each is computed from the live corpus when this page is served, not typed into it.
| Finding code | Share of scans | Guide |
|---|---|---|
MACHINE_FILE_CACHE_STALE | 0.7% | Does llms.txt actually do anything? |
MACHINE_FILE_CACHE_SPLIT | 0.1% | Does llms.txt actually do anything? |
ORIGIN_BLOCKED_BEHIND_CACHE | 0.3% | Is Cloudflare blocking AI crawlers on your site? What changes on 15 September 2026 |
Every code, its rule and its current rate: the dataset page. Scan a site to see which apply to it.
Where cache-buster comes up on this site
- Is Cloudflare blocking AI crawlers on your site? What changes on 15 September 2026Then compare identities on the bare URL, never with a cache-buster, because a crawler never appends one: curl -s -o /dev/null -w "%{http_code} %{size_download}\n" -A "Mozilla/5.0" https://yoursite.com/ curl -s -o /dev/null -w "%{http_code}…
- How to check whether AI crawlers can read your siteFetch the bare URL first, the cache-buster second This is the check people get backwards, and it is the single most common defect in the entire dataset.
- How to rank in ChatGPT: the part that is actually in your controlSTALE_CACHE_SERVED fires on of scans , and it hides from testing because adding a cache-buster to the URL bypasses the cached copy and returns the correct file.
- Do AI crawlers respect robots.txt?It must be text/plain . curl -s https://yoursite.com/robots.txt — the body, on the bare URL, with no cache-buster appended. curl -s https://yoursite.com/robots.txt | grep -i sitemap — the declaration, then fetch what it points at. curl -s -o /dev/null -w…
- How to write an llms.txt, and how to check it is actually being servedCheck the bare URL, with no cache-buster, because a crawler never appends one: curl -sI https://yoursite.com/llms.txt Two things must be true.
Terms this definition uses
Related terms in HTTP, edge and rendering
The delivery layer between an origin and a client: proxies, caches, redirects, status codes and the headers that decide what a crawler actually received.
Origin server · Reverse proxy · CDN · Edge node · WAF · Bot score · TLS handshake · DNS resolution · DNS timeout · Connection timeout · Read timeout · Redirect chain · Redirect loop · 301 redirect · 302 redirect · 307 redirect · 308 redirect · 304 response · 404 response · 410 response · 429 response · 500 response · 502 response · 503 response · 504 response · HEAD request · GET request · Content type · MIME sniffing · Content encoding · Compression · Brotli · ETag · Last-Modified · If-None-Match · Cache hit · Cache miss · Cache key · Vary header · Stale response · Stale-while-revalidate · Edge redirect · Origin bypass · Response parity · Header parity · hreflang · canonical URL · HSTS · HSTS preload list · Content-Security-Policy · CSP nonce · edge cache · cache split · Cache-Control · Age header · render-blocking resource · payload text share · lazy loading · 404 and 410 status codes
Questions about cache-buster
What is cache-buster?
A random query parameter appended to a URL so that the request misses every cache keyed on the URL and reaches the origin.
What does cache-buster not show or guarantee?
It is a measurement tool, not a fix: it shows what the origin serves now, and it says nothing about what the edge is still serving to everyone who asks for the bare URL.
How does CrawlCheck measure cache-buster?
Through the finding codes MACHINE_FILE_CACHE_STALE, MACHINE_FILE_CACHE_SPLIT, ORIGIN_BLOCKED_BEHIND_CACHE, each with a stated rule, evidence bytes and a live share of scans on the dataset page.
Which area of the glossary does cache-buster belong to?
HTTP, edge and rendering: The delivery layer between an origin and a client: proxies, caches, redirects, status codes and the headers that decide what a crawler actually received.
← cache split · Cache-Control →
See it in the full glossary · 668 terms across 19 areas.