lt.rt.ht - Utilities | RTEdge.net docs

Syntax

plain

https://lt.rt.ht/

The page has no URL parameters: you choose or type a URL in the page. A <random-N-chars> placeholder in that URL is replaced with N random characters for every fetch, which gives each fetch a cold path.

Parameters

The page has no URL parameters. Its controls are:

URL: The target, with a list of presets. A double click clears the field.
Run One: Tests the URL in the field.
Run Random: Tests the presets that are marked random.
Run All: Tests the presets that are marked all: four RTEdge.net targets, and the Deno Deploy, Vercel and Akamai samples.
CORS: Off by default. Off means the requests use mode: "no-cors", and the page cannot show the HTTP status.
Details: Shows a log of every fetch.
Fetch: The number of fetches for each target. The default is 25, and the range is 1 to 100.
Redo: The number of extra passes after the first. The default is 1, and the minimum is 0. Each pass clears the samples of the previous one, so with the default every target is measured twice, and only the second pass, on a warm connection, stays on screen.

Enter runs one test when no input has focus, or all tests when Run One is disabled.

Presets

The presets come in groups:

Cloudflare's own cdn-cgi/trace endpoints.
RTEdge.net: a host request, a system request, a worker request and an asset request, and variants on random subdomains.
Samples on Cloudflare Workers, and on Workers for Platforms.
ip.rt.ht and ip.efn.kr. See ip.rt.ht and rq.rt.ht.
Elefunc's sites.
Other platforms: samples on Deno Deploy, Vercel, Akamai and val.run.
RTCode.io assets.

Response

The page shows its results on screen. Each target gets N sequential fetch() calls, 50 ms apart, timed with performance.now(). The time includes DNS, connection setup and TLS on a cold connection, so the first sample of a cold pass is usually the slowest. Because the default Redo keeps only the second pass, the numbers on screen mostly reflect reused connections, except for the presets with a random hostname.

The page shows the maximum, the average and the minimum for each target, an optional log of every fetch, and sparklines on one shared scale. The results include the network round trip and the server time, as your browser sees them. With CORS off, the HTTP status is unknown and the page shows -. A preset with <random-N-chars> gets a fresh random hostname for every fetch, which defeats connection reuse and caches.

Examples

Link to the tester

HTML

html

<a href=//lt.rt.ht>Test our speed</a>

Result

CORS and limits

The tester runs in your browser, so each target is fetched from your network, and the target does not need to allow lt.rt.ht: with CORS off, the requests use no-cors and the status stays hidden. Turn CORS on to see statuses for targets that send CORS headers.
The fetch count is limited to 1 to 100 for each target, and 50 ms pass between two fetches.

Status

lt.rt.ht is available. Its behavior was checked on 2026-10-04.

`lt.rt.ht`