ua-tracer by Paul Kinlan

trace mJRLc1eM

ua-tracer

what does a user agent actually fetch, follow & run?

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Trace mJRLc1eM

First seen: 2026-10-08 13:55:49.238 UTC
User-Agent: Mastodon/4.6.7 (http.rb/5.3.1; +https://ma.fellr.net/) Bot
Bot verification: Not a known bot (no IP-range check applies).

What this user agent did

Directly-referenced assets:

✗ fetched CSS ✗ fetched JS ✗ fetched image ✗ fetched font (HTML)

Document-level link hints:

✗ fetched favicon ✗ fetched apple-touch-icon ✗ fetched web manifest ✗ fetched preload ✗ fetched prefetch

Second-level follows (proves it parsed the linking file):

✗ followed CSS background-image ✗ followed CSS @font-face ✗ followed manifest icon ✗ followed CSS @import

Frames (does it descend into iframes?):

✗ fetched iframe document ✗ descended into iframe (loaded inner image)

Reporting (a report-only CSP is violated by inline styles; reports can arrive via HTTP headers with no JS, or via in-page beacons):

✗ sent a CSP/Reporting report (any path) ✗ delivered via report-uri/Report-To header (no JS) ✗ delivered via in-page beacon (securitypolicyviolation / ReportingObserver)

Social embed (Open Graph / Twitter card images):

✓ fetched og:image ✗ fetched twitter:image

JavaScript execution:

✗ EXECUTED classic JS ✗ EXECUTED ES module ✗ posted client timing

Server-side request waterfall

Every request the server received for this trace, in receive order. +ms is the delta from the homepage request.

ReceivedΔKindMethodUser-Agent
2026-10-08 13:55:49.238 UTC +0 ms homepage GET Mastodon/4.6.7 (http.rb/5.3.1; +https://ma.fellr.net/) Bot
request headers (12) 
{
  "accept": "text/html",
  "accept-encoding": "gzip",
  "accept-language": "en, *;q=0.5",
  "connection": "close",
  "date": "Thu, 08 Oct 2026 13:55:49 GMT",
  "host": "uatracer.com",
  "traceparent": "00-65957c7d7785bafa026dcb073537b83d-6bf812fa1151d1cc-01",
  "tracestate": "",
  "user-agent": "Mastodon/4.6.7 (http.rb/5.3.1; +https://ma.fellr.net/) Bot",
  "via": "HTTP/1.1 ams.vultr.prod.deno-cluster.net",
  "x-deno-userspace-traceparent": "00-65957c7d7785bafa026dcb073537b83d-00431dbfcb796d73-01",
  "x-deno-userspace-tracestate": ""
}
2026-10-08 13:55:52.277 UTC +3039 ms Open Graph image GET Mastodon/4.6.7 (http.rb/5.3.1; +https://ma.fellr.net/)
request headers (10) 
{
  "accept-encoding": "gzip",
  "connection": "close",
  "date": "Thu, 08 Oct 2026 13:55:52 GMT",
  "host": "uatracer.com",
  "traceparent": "00-124c380155bbeb540685c1719a431291-03e9aa0cae802285-01",
  "tracestate": "",
  "user-agent": "Mastodon/4.6.7 (http.rb/5.3.1; +https://ma.fellr.net/)",
  "via": "HTTP/1.1 ams.vultr.prod.deno-cluster.net",
  "x-deno-userspace-traceparent": "00-124c380155bbeb540685c1719a431291-b1a8f4e996838c38-01",
  "x-deno-userspace-tracestate": ""
}