One Swiss Knife in the exact shape of your life.

Interest & Loan

A loan and interest reckoner that runs in your browser and stores nothing: punch the numbers, read the answer, close the tab.

Live · runs in your browser · no network

This is not a screenshot. It's the real tool, running right here: go on, put something in it.

Open the demo full-screen: /demos/interest-loan.html

Forged into a knife, this tool ages with use: the blades you reach for wear soft, entries you tend keep their bloom, and the years travel with the file through every reforge.

The loan brochure is cheerful, the rate looks small, and the total over twenty years is a number they printed in a lighter grey. Interest & Loan does the honest arithmetic — what a rate compounds into, what a loan really costs over its life. It computes the figures in front of you and keeps none of them, so you can wonder about money in complete privacy.

KindReckoner · computes, stores nothing
CategoryReckoners
Weight1
Manual:

Standing facts

In ten years

Interest & Loan computes; it doesn't hoard. Open the file in 2036 and it will do the same arithmetic it does today, because the arithmetic is written into the file and nothing about it needs a server to agree.

If Offline.Ltd closes tomorrow, nothing on your machine notices. That isn't a marketing promise; it's simply what a file is.

Getting your data out

There is nothing locked in to get out: copy the numbers, or keep the file. Either way you owe no one a request form. No export queue, no "we'll e-mail you a link within 48 hours", no format that only one vendor can read.

Copy the file to a USB stick, a NAS, a folder your devices already sync. It runs on Windows, macOS, Linux, Android and iOS, online or off, because a browser is the only thing it ever needed.

Who else sees this

Nobody. Interest & Loan works out its answer in your browser and forgets it the moment you close the tab: there is no store to breach, because nothing is stored. There is no account, no telemetry, no analytics, and no code in the file that opens a network connection, pull the cable and watch it carry on working. How privacy works across the Reckoners tools →

Questions people ask

01

Can I check my finances in this without them being stored anywhere?

That is the whole design. It is one HTML file running offline in your browser; it computes your numbers on the spot and stores nothing. No account, no cloud, and your what-ifs never leave the page.

02

How do I see what a loan will really cost me?

Enter the amount, the rate, and the term, and it works out what the borrowing adds up to. Seeing the full figure before you sign is the entire point of the exercise.

03

Can it show me how savings grow with compound interest?

Yes — give it a starting sum, a rate, and time, and it shows you what compounding does. It is the same arithmetic banks use, minus the marketing.

Go deeper on Interest & Loan

More Reckoners

Fits your knife at weight 1. Nothing here is final, Knife follows Life. Reforging within your tier is free, forever. Add it, drop it, reforge it later; the file stays yours either way.

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