---
title: "Free financial tools"
description: "How the free calculators at banksync.io/tools work, where their rates come from, and what they deliberately do not do."
section: "Free tools"
canonical: "https://banksync.io/docs/free-tools/free-financial-tools"
---

BankSync publishes a set of free financial tools at [banksync.io/tools](/tools). They need no
account, store nothing, and send nothing you type to a server. This page explains how they are
built, because the useful thing about a calculator is whether you can check its work.

## Every answer is computed before the page reaches you

Each tool page ships a complete, correct result in its initial HTML. The number, the rate table,
the methodology and the questions are all there before any JavaScript runs.

That matters for two reasons. A search engine or an AI assistant that does not execute JavaScript
still sees a real answer rather than an empty shell. And if scripts fail to load, the page still
answers the question it was built for — you simply cannot change the inputs.

Once the page hydrates, changing an input recomputes in the browser. Nothing is sent anywhere.

## Where the rates come from

Tools fall into two groups.

**Pure arithmetic** — compound interest, loan repayments, break-even, rule of 72. The maths is the
same everywhere, so these are one global page with a currency selector. There is no such thing as
an Australian compound interest formula, and splitting one would be padding.

**Statutory** — income tax, stamp duty, superannuation caps, mortgage insurance. These read from
dated rule tables that record the figure, the authority it came from, and a link to the page it
was published on. Every one of those sources is listed at the bottom of the tool that used it.

Rule tables are **additive**. A new tax year adds a file; it never edits an old one. That is what
lets a page say "as at 2026-27" and mean it, and it is why a tool can still reproduce last year's
answer.

## A human signs off every statutory figure

A rate table is not usable until a person has checked each value against the authority that
published it and confirmed it. That confirmation is a deliberate, interactive step — it cannot be
performed by a script or an automated agent, by design.

Until it happens the tool stays a draft: no page, no link, not in the sitemap. This is why the
directory sometimes lists fewer tools than exist in the codebase. A calculator that is merely
plausible is worse than one that is absent, because a wrong tax figure is a trust failure rather
than a rounding error.

## What each page shows you

Every tool carries the same structure:

- **The result**, with the supporting figures that explain it.
- **How this is calculated** — the actual formula, and the reasoning behind the parts that catch
  people out.
- **A worked example** with real numbers you can follow end to end.
- **What this assumes** — stated plainly, because every calculator assumes something.
- **Where this commonly goes wrong** — the traps, naming the specific rule.
- **Sources** — the authority pages behind every statutory figure used.

There are no author bylines. The citations are the trust signal, which is why a dead link is
treated as a defect rather than a cosmetic problem.

## What these tools do not do

They do not know anything about you. They are not advice, they do not account for your
circumstances, and they cannot tell you what a lender or a tax authority will decide. They do
arithmetic on figures you supply, using published rates, and they show their work.

For your own numbers rather than hypothetical ones, [BankSync](/product/bank-feeds) syncs your real
transactions and balances into a spreadsheet, Notion, or a database — which is the difference
between modelling a budget and measuring one.