The Toolshed
everyday tools, no assembly required

One shed.
Every tool you reach for.

Mortgage math, a car payment, a QR code, your BMI — the small calculations that show up in ordinary weeks, kept in one plain place. Nothing to install, nothing to sign up for.

13
tools on the pegboard, more get hung up over time

About these tools

The Toolshed is a free collection of browser-based utility tools built for the calculations that come up in ordinary life — financing a home or car, splitting a restaurant bill, checking your BMI, converting between units, generating a QR code or a strong password. Every tool runs entirely in your browser with no account required and nothing stored or tracked.

Money tools

The mortgage calculator uses a standard amortization formula to show your monthly payment, total interest, and the full cost of a home loan over its term. The car loan calculator applies the same math to vehicle financing, with guidance on how loan term length affects total cost. The tip & split calculator handles the arithmetic of splitting a bill evenly across any number of people, with context on tipping norms by service type and country. The currency converter pulls live exchange rates from the European Central Bank and explains how financial institutions mark those rates up when you actually exchange money.

Body and time tools

The BMI calculator computes your body mass index and explains the four standard WHO categories, along with a clear-eyed look at where BMI misleads — particularly for muscular individuals, older adults, and certain ethnic groups. The age calculator finds the exact difference between any two dates in years, months, and days, handling variable month lengths and leap years correctly. The time zone converter uses your browser's IANA time zone database to convert any date and time between any two zones, correctly accounting for daylight saving time rather than applying a fixed offset.

Everyday tools

The QR code generator turns any URL, text, Wi-Fi password, phone number, or other content into a downloadable QR code — generated entirely in your browser, so sensitive content never leaves your device. The date converter renders a single date in every common format at once: ISO 8601, US and EU formats, long written form, Unix timestamp, Julian YYDDD ordinal date, and ISO week number. The unit converter handles length, weight, and temperature with the exact internationally defined conversion factors. The password generator uses the browser's cryptographic random number generator (not Math.random) to produce genuinely unpredictable passwords. The file size converter converts between bytes, KB, MB, GB, and TB in both decimal and binary bases, with an explanation of why a "1TB" drive shows as 931GB in Windows. The GPA calculator computes a credit-weighted grade point average on the standard US 4.0 scale.

How it's built

Every tool is a plain HTML page — no frameworks, no build pipeline, no server-side processing. Calculations happen in the browser using vanilla JavaScript. The currency converter fetches live data from the European Central Bank's public API; all other tools are fully offline-capable once the page has loaded. Source code for the shared logic lives in shared.js. Hosting is on Netlify. For questions, bugs, or suggestions, use the feedback form — a real person reads every note.