Which Browser Tools Actually Stay Local? We Put Ours on a Network Monitor

By Lucian — builder & engineer, LK Forge

“Runs in your browser, nothing uploaded” is easy to claim and easy to fake. So we tested our own: we opened 15 LK Forge tools across nine categories with the browser’s network panel recording every request, and wrote down exactly where each one went. The short version — not one sent the text, file or image you give it — and the honest exceptions are all below.

September 4, 2026  ·  6 min read  ·  measured live, reproducible in your own browser

How we measured it

Claims about privacy are only worth what you can check. So the method here is one anyone can repeat: load the live tool, let it run, and ask the browser itself for the complete list of hosts it contacted. Every browser keeps that list — the Network tab shows it visually, and the Performance API returns it as data. We took the data, dropped every request to lkforge.com, and looked at whatever was left.

Fifteen tools, nine categories: a JSON and SQL formatter, a word counter, a CSV converter, a Base64 encoder, a PDF splitter, an EXIF remover, a loan calculator, a chess game, and the live-data trackers for IP, asteroids, volcanoes, earthquakes, the ISS and currency. Not every tool — a representative slice, weighted toward the ones people paste sensitive things into.

Nine tools that talk only to themselves

The formatters, the converter, the PDF splitter, the EXIF remover, the calculator, the chess engine — every request they made went to lkforge.com: the page, its stylesheet, its JavaScript, and the fonts — which load first-party from lkforge.com, so your browser never contacts Google Fonts. Once that code has loaded, the tool does its job with no further network activity at all — you can turn the network off and keep working. There is no request carrying your input because the browser is doing the work, not a server.

The proxy tools: your browser only ever talks to lkforge.com

A few tools genuinely need outside data — where an asteroid will pass, which volcanoes are erupting, what your public IP is. The interesting part is how they get it. What’s My IP, the Asteroid Tracker and the Volcano Tracker never contacted NASA, the Smithsonian or an IP-lookup service from your browser. Every request went to an /api/ path on lkforge.com — an edge worker fetches the source server-side and relays the result. From the third party’s point of view, LK Forge asked; your browser and your IP stayed with us.

The direct tools: what actually leaves

Three tools did contact an outside host directly: the Earthquake Tracker fetched earthquake.usgs.gov, the ISS Tracker fetched api.wheretheiss.at, and the Currency Converter fetched open.er-api.com. In each case the request asks for public data — a global quake feed, the station’s current coordinates, the day’s exchange-rate table — and carries nothing personal. The currency tool, for instance, downloads the rate table once and then does every conversion locally.

Measured live on 4 September 2026. “Browser contacts” excludes the page’s own assets on lkforge.com; every tool also loads one cookieless analytics beacon (static.cloudflareinsights.com), which receives page metadata, not tool content.

The honest exceptions

“Nothing leaves your browser” is not true of every feature on the site, and it would be dishonest to imply it. A handful of tools have to send something to do their job — you cannot look up a domain’s DNS, or identify a plant from a photo, without sending the domain or the photo. Here is every one we know of, and exactly what it sends. This list existing, in the open, is the point: the claim holds because the exceptions are named, not hidden.

Confirmed in the tools’ source; these send input by necessity and are not part of the 15 “no input leaves” measurements above. Voice dictation additionally relies on the browser’s built-in Web Speech API, which in some browsers sends audio to the vendor’s own cloud — a property of your browser, not of LK Forge.

Reproduce this in ten seconds

You don’t have to trust the table. Open any tool, open the browser console (F12 → Console), and paste this. It prints every host the page contacted that isn’t lkforge.com — the same data behind every row above.

const hosts = {};
for (const e of performance.getEntriesByType('resource')) {
  const h = new URL(e.name).host;
  if (!h.endsWith('lkforge.com')) hosts[h] = (hosts[h] || 0) + 1;
}
console.table(hosts);

On a fully-local tool you’ll see one line: the analytics beacon. On a live-data tool you’ll see exactly the host in the table — and nothing carrying what you typed. The stronger test still works too: load the tool, kill your Wi-Fi, and keep using it. Anything that survives offline was never talking to a server.

Try one and watch it yourself

Every tool on the site is free and needs no account. Open the Network tab and see for yourself.