About ToolShelf

What this is

ToolShelf is a set of small web tools for everyday calculations. The kind of sum you would otherwise do twice on your phone because you were not confident the first time.

There are 93 tools so far, across 10 categories: money and loans, dates and times, text, images and files, tools for freelancers and small businesses, and a group of calculators for Muslim readers covering prayer times, zakat and the Hijri calendar. You can see the full list or start from the homepage.

New tools get added slowly, one at a time. Each one has to earn its place by being genuinely more useful than whatever is already at the top of the search results for it.

Why it exists

Most tool sites work, technically. You arrive from a search, find the input field below three ad slots, type your numbers in, press Calculate, and get back a single figure with no indication of how it was reached or what it assumed. If the number looks off, you have no way of telling whether you made the mistake or the site did.

That last part is the real problem. A calculator you cannot check is a calculator you have no reason to trust, and trusting it is the whole point of using one.

The rules every tool follows

The working is shown. Results come with the figures behind them: the subtotals, the thresholds, the rate that was applied. You should be able to follow the answer on paper if you want to.

Nothing leaves your browser. The arithmetic runs on your own device. Nothing you type is uploaded, stored or logged, and closing the tab clears it. The same goes for the image tools: photos you compress or convert are read by your browser and never sent anywhere. There are no accounts, so there is nothing to sign up for and nothing to delete.

Some things on the site do talk to somebody else, and each says so where you meet it. The email deliverability checker has to ask a public DNS resolver about the domain you give it, because a browser cannot make a DNS query itself. And ToolShelf counts visits with Google Analytics and carries Google ads to pay for the hosting, both of which you are asked about once and can turn off on the cookie policy page. None of them ever sees what you type into a tool.

Assumptions are stated, not buried. The zakat calculator is the clearest case. The nisab threshold can be based on gold or on silver, the two give very different answers, and scholars differ on which applies, so the tool asks instead of quietly picking one. Metal prices work the same way. They move daily, so the tool asks for today’s figure rather than shipping a number that will be wrong by next month.

A tool that cannot answer says so. The inheritance calculator lists the heirs it handles and refuses the cases it does not, rather than producing a confident number for a situation it was never built for. The break-even calculator tells you when there is no break-even point at all. That is more useful than an answer you cannot rely on.

How it is built and checked

It is a static site. No account system, no database of your calculations, no server doing the maths. Each tool’s calculation is kept separate from its interface and covered by its own tests, including the awkward cases: zero, negative numbers, division by zero, and values sitting right on a threshold. A calculator that is quietly wrong in one edge case is worse than no calculator, because you will not know.

Where a figure can be checked against a published source, it is. Loan payments are tested against the standard mortgage figures, prayer times against published almanac data, and the Hijri calendar against the same civil calendar your operating system uses.

Pages are plain HTML by default and load quickly on a slow connection, which is the condition most people are actually in when they need one of these.

Who makes it

ToolShelf is a small independent project rather than a company. That shapes what it is. There is no growth target, so there is no reason to add sign-up walls, email capture, or a tenth tool that duplicates the ninth.

It is run alongside other work, so replies to email take a few days rather than a few hours.

How it is paid for

The tools are free and there is nothing to buy. The running costs are small, and the plan is to cover them with advertising on some pages. If and when ads appear they will be clearly separated from the tool and its results, and they will never change an answer, reorder a list, or sit between you and the thing you came for.

No advertiser gets to influence what a tool says. If that ever stopped being true, the honest thing would be to say so on this page.

What is next

More tools, added slowly. If there is one you would genuinely use, or if a tool here gives you an answer you think is wrong, tell me about it. A specific report about a specific number is the most useful thing anyone sends.