About YoursTools

What this site is

YoursTools is 880 tools across 14 categories: loan and investment calculators, health metrics, unit converters, developer utilities, PDF and image processing, colour and accessibility checkers, and a long tail of things people need occasionally and do not want to install software for.

What they have in common is that every one of them computes on your device. When you enter a salary, select a contract to merge, or paste an API response, that data stays in your browser. There is no upload step and no server-side processing, which means there is nothing for us to log, retain or lose.

That is a design constraint rather than a promise, and it is the reason we describe it as verifiable: open your browser's network tab and use any tool, or simply disconnect from the internet after a page has loaded and watch it keep working. We wrote up the reasoning, and what it costs us, in why we run everything in your browser.

The catalogue

Category	Tools	Examples
Unit converters	150	Length, mass, temperature, pressure, data
Developer	148	JSON, Base64, hashing, encoding, UUIDs
Finance	116	EMI, amortisation, SIP, compound interest, tax
Maths	100	Percentages, statistics, geometry, algebra
Health	99	BMI, BMR, calories, macros, body composition
Image	53	Resize, compress, convert, crop, EXIF
Text	47	Counters, case conversion, cleanup, frequency
Colour	40	Pickers, palettes, WCAG contrast, blindness simulation
SEO	34	Meta tags, SERP preview, keyword density
Security	32	Password generation, entropy, hashes, AES, TOTP
PDF	22	Merge, split, compress, protect, convert
Date & time	16	Differences, age, time zones, working days
Miscellaneous	12	QR codes, barcodes, random pickers
Education	11	GPA, grades, study planning

How a tool gets built

Every calculator is a JavaScript function with a declared set of inputs, ranges and units, running on a shared engine. That shared engine is deliberate: it means validation, error handling, unit labelling, keyboard behaviour and screen-reader announcements exist once and behave identically everywhere, instead of being reinvented 880 times with 880 opportunities to get it wrong.

For each tool we do the following:

1. Find the authoritative definition. The SI brochure for units, the published equation for a health metric, the RFC for a data format, the standard amortisation identity for a loan. Not another website.
2. Decide which convention applies where more than one exists, and say so on the page. Mifflin-St Jeor rather than Harris-Benedict; reducing balance rather than flat rate; WCAG 2.x rather than APCA. Silent convention choices are how two correct calculators disagree.
3. Implement it directly, in full double precision, rounding only for display.
4. Declare ranges and units per field, so an out-of-range value produces an error naming the field rather than a plausible-looking wrong answer.
5. Verify against a worked example computed by the real tool code, which is what appears in the "worked example" section of each page. Those numbers are generated by running the tool, not typed in by hand, so they cannot drift away from what the page actually does.

Where a formula has well-known limitations, we say so on the page rather than burying it. BMI is a population statistic misapplied to individuals; TDEE calculators carry a ±15% error bar; a loan calculator cannot know your lender's fee schedule. A tool that presents an estimate as a fact is worse than no tool.

Editorial standards

We write everything ourselves. We do not accept guest posts, sponsored articles, or paid links, and we do not sell placement in our tool listings. If we ever do, it will be labelled.

We cite the standard, not the consensus. Our articles name the specific source a claim rests on: RFC 8259, the 1959 international yard and pound agreement, NIST SP 800-63B, WCAG 2.2: so you can check it rather than take our word for it.

We correct errors publicly. When a formula is wrong we fix the tool and record what was wrong, when it changed, and what the correct method is. We do not quietly edit a number and move on.

We do not give advice. This is the line we hold most carefully. Our finance tools do arithmetic; they do not tell you whether to borrow. Our health tools compute standard indices; they do not diagnose anything. We are not licensed to advise on medical, financial, legal or tax matters and we will not imply otherwise. Where a subject is genuinely consequential, the page says so and tells you to speak to a professional.

Accessibility

We target WCAG 2.2 Level AA. In practice that means text and interface controls are tested for contrast in both light and dark themes with alpha compositing accounted for, every control is reachable and operable by keyboard, form fields carry real labels, results are announced to screen readers when they change, and information is never conveyed by colour alone.

We do not claim to have caught everything. No site that size honestly can. If something is unusable for you, tell us and we will treat it as a defect rather than a feature request.

How the site is funded

Advertising. That is the whole model, and we would rather state it plainly than let you work it out.

The tools are free with no account, no usage cap and no paid tier, and we intend to keep them that way. Ads are served by Google AdSense, which is a third party that sets its own cookies: that is separate from the tools and gives nobody access to what you type, because those values never leave your device in the first place.

We implement Google Consent Mode v2, so visitors in the EEA and UK are asked before any advertising or analytics cookie is set, and everything stays denied until you choose. Rejecting non-essential cookies does not degrade any tool. Details are in our cookie policy and privacy policy.

One consequence worth naming: because the tools are client-side, we genuinely cannot see what people compute. Our analytics records that a page was viewed. It cannot record the contents of a form field on that page. That is good for you and mildly inconvenient for us, and it is the trade we chose.

What we deliberately do not build

The client-side constraint rules out an entire category of tool, and we would rather have a gap than quietly break the rule:

• Anything that needs live external data, such as currency conversion at today's rate, share prices, WHOIS lookups, real backlink indexes or IP geolocation. All of these require a server call by definition.
• Anything requiring an account, saved history across devices, or server-side storage.
• Anything that gives advice rather than computing a documented quantity.

There is also a practical limit: large files are processed using your machine's memory and processor. A 200 MB PDF is fine on a modern laptop and may struggle on an older phone. A server-based tool would perform the same for everyone. We think the privacy trade is worth it, but it is a trade and not a free win.

Those gaps are easiest to see next to the services that do fill them, so we have written them up honestly in our comparisons with other tool sites: what Smallpdf and iLovePDF do that we cannot, and where CodeBeautify and JSONFormatter.org have the wider catalogue.

Getting in touch

The most valuable message you can send us is one saying a calculation looks wrong, with the inputs you used and the answer you expected. That goes straight to the top of the list. Tool requests, accessibility problems and privacy questions are all welcome too.

Everything you need is on the contact page, including what to include so we can reproduce a problem quickly.