Privacy

Your data never leaves this tab

When you drop a file here, your browser reads it. The file is parsed, the surface is interpolated and the map is drawn by code running on your own machine. Nothing is uploaded, nothing is stored on a server, and there is no server that could store it.

That includes Excel workbooks. Reading one means unzipping it and parsing XML, which this site does in the browser rather than by sending the file somewhere that finds it easier.

There are no accounts and no cookies

You cannot sign up, because there is nothing to sign up to. No email address is collected, no account is created, and no cookie is set for any purpose — not for sessions, not for preferences, not for analytics.

Your theme choice is kept in your browser’s local storage, which never leaves your machine and is not sent with any request.

What this page keeps, it keeps on your machine

So that closing a tab by accident does not cost you an afternoon, this page saves the file you dropped and the figure you were building — the settings, the wording you typed, the wells you left out, and the background picture if you added one — in your own browser’s storage. It is offered back the next time you visit, and it is never opened without you clicking to open it.

Saved site templates are kept the same way. A template holds the well names and positions of a site, the settings, the wording, and the background picture with the two points that place it — so that next quarter is one drop rather than an afternoon. It holds no readings, no dates and no values.

None of it is sent anywhere, because there is nowhere to send it. It sits in this browser on this machine, another browser or another computer knows nothing about it, and clearing this site’s data in your browser settings deletes all of it. Discard on the banner and Delete on a template do the same thing for one item at a time.

There is no analytics and no tracking

No analytics script, no tag manager, no session recorder, no heatmap, no advertising pixel, no third-party fonts. Nobody is told that you visited, what you mapped, or how long you stayed.

The one case where a request leaves your machine

A figure can be drawn over a street or aerial background. Doing that means asking a map server for the images, and each request necessarily says which square of the world it is for — which tells that server roughly where your site is.

So it is off, and it is never turned on quietly. It is offered only under Background beside your data, only for files whose coordinates can be turned into latitude and longitude, and only through a dialogue that states exactly this before anything is requested. Agreeing lasts for that visit: close the tab and it is off again, and nothing about it is written into your saved work.

Your data itself is never sent, and that is not a promise about intent — it is what a map-image request is. It carries three numbers describing a square of the world. Not the readings, not the well names, not the file, not the figure. The server also learns your network address and that the request came from this site, exactly as it would for any image on any web page.

The other kind of background — a site plan or aerial of your own — involves nobody. You supply the picture from your own machine, it is read here the same way your data is, and it never leaves the tab.

How to check all of this rather than believe it

Open your browser’s developer tools, go to the Network tab, and load a file. You will see the requests that fetched this page and its code, and then nothing further. Drop a file, change the contour interval, drop in your own site plan, export the figure — no request is made.

The one thing that does make requests is the street or aerial background described above, and you can watch that too: turn it on and the Network tab fills with map images, and only map images. Turn it off, or leave it off, and the tab stays empty.

Better: load the page, then turn off your network connection entirely. Everything still works, because everything was already on your machine.