HTTP response inspector

What this inspector checks

Start a single explicitly authorised request from your browser to our fixed diagnostic endpoint. The server validates a signed test capability, reserves a bounded quota and returns a small versioned JSON response. The inspector checks the run identifier, sequence number, expected method and endpoint before accepting the response. A successful HTTP status without the expected response contract is not treated as a validated result. This is a controlled-endpoint diagnostic, not a general-purpose client for arbitrary APIs.

How to run a useful comparison

Open the inspector in the same browser you use for the affected application. Keep the tab visible and close unrelated heavy browser work where practical. Select Inspect response, then record the HTTP status, validated response and any browser-exposed protocol. Repeat after changing one condition, such as disconnecting a VPN or moving to another approved network. This tool does not automate that change or identify the physical route. A single sample is useful for checking this response path, not for estimating long-term reliability.

Reading the evidence

HTTP status is the response observed by Fetch. Body validation checks that the response belongs to this run rather than an unrelated or malformed reply. The displayed header list is deliberately restricted to content type, cache policy, content-type protection and the diagnostic method version. The negotiated protocol is taken from the matching Resource Timing entry when available. The tool does not request a particular HTTP version, inspect a TLS certificate or infer a missing protocol value.

Timing and attribution limits

Observed elapsed time includes browser scheduling, the connection path, Worker processing, session-quota coordination and response-body consumption. It is not raw ICMP ping or isolated wire latency. Existing browser main-thread checks flag contaminated or insufficient timing evidence; a very short single request may be too brief for those checks. A Fetch failure cannot by itself distinguish DNS, TLS, CORS, a disconnected network or an application error. Percentile summaries need more than one accepted sample, so p95 is unavailable for this one-request tool.

Budgets, privacy and next checks

The request has a two-second deadline inside a twenty-second run budget. The response reader accepts at most 4 KiB. The existing admission system reserves an 8 MiB allowance, but does not send that amount; each probe conservatively debits 256 KiB of the allowance. Stop cancels outstanding work and requests lease revocation. Results remain in page memory unless you export JSON. Reports exclude cookies, capabilities, IP addresses and raw request headers. Use the response stability monitor for repeated observations, or the existing upload check to compare responsiveness while an actual controlled transfer competes.

Method references and related tools

W3C Resource Timing explains browser timing and protocol visibility. Cloudflare Workers Response API documents the controlled response mechanism. These standards do not certify the measured network path.

Response stability monitor · All tools · Overall measurement methodology