UnitHub

app.lucaskalil.com/unithub

A fast, exact, fully client-side unit converter — 18 categories, 236 units, in English and Portuguese. Built so that adding a unit is one line of data, not a component change.

Conversions you can check.

Nothing is sent anywhere. There is no backend, no analytics, and no third-party request of any kind — the fonts are self-hosted precisely so that stays true.

What it does

• Bidirectional conversion — type in either field, the other recomputes.
• Shareable URLs — /:category?from=km&to=mi&v=10, restored exactly on open, in any language.
• Signature scale ruler — a dual-graduation ruler where a value and its conversion land on the same physical point.
• All-units table — every unit at once, with per-row copy of the unrounded value.
• English and Portuguese (BR) — number formatting follows the language; the URL never does, so a shared link resolves identically for everyone.
• Dark / light, mobile-first, keyboard-navigable, prefers-reduced-motion respected.

Kept honest

The reason this exists. Most converters quietly flatten distinctions that change the answer:

• KB (×1000) vs KiB (×1024) are separate units, each with a tooltip. Same for bits vs bytes in data rate.
• A troy ounce is heavier than an ounce, but a troy pound is lighter than a pound. Both sets ship, both labelled.
• Torque is not energy. lbf·ft and ft·lb have byte-identical factors, and they still live in different categories, because a moment is not work.
• Out-of-gamut colours are reported, not hidden. OKLCH can name colours sRGB cannot show; converting one clips it, and the swatch says so and shows the ΔE it cost.
• CMYK ships flagged. Without an ICC profile the numbers are a convention, and the UI says that rather than implying a measurement.
• Base 58 is deliberately absent. Bitcoin's base58 omits 0, O, I and l, so a plain positional base 58 would be subtly wrong rather than merely approximate.

Categories

Group	Categories
Size & space	distance (27), area (12), volume (37), angle (8)
Mass & motion	weight (26), speed (7), force (12), torque (9), pressure (11)
Time & frequency	time (13), frequency (9)
Energy & heat	energy (12), power (11), temperature (4)
Data	file size (12), data rate (12)
Dev tools	number base (8 presets, any radix 2–64), color (6 models)

Architecture

Three engine shapes, each routing through a hub the way a category routes through its base unit:

Kind	Hub	Component
scale	the category's base unit	Converter
radix	a BigInt, exact at any size	BaseConverter
color	linear-light sRGB, unclamped	ColorConverter

target = value × factor(source) ÷ factor(target)

• src/data/ — categories as data. The groups registry in data/index.ts drives the menu, the home page and the routes, so they cannot fall out of sync. Non-linear categories (temperature) use toBase / fromBase instead of factor.
• src/lib/ — pure, fully tested, no React: convert.ts (engine), numberBase.ts (radix 2–64 via BigInt), format.ts (parsing and Intl formatting), urlState.ts (state ↔ query), color/ (the colour engine).
• src/i18n/ — every user-visible string. A locale is one file plus one registry entry, and a missing key is a compile error, not a silent English fallback.
• src/components/, src/pages/ — the UI.

Add a unit

// src/data/categories/distance.ts
{ id: "fur", factor: 201.168, symbol: "fur", labelKey: "units.fur" }

// src/i18n/en.ts   (and pt.ts — a gap fails the test suite)
"units.fur": "Furlong",

That's it. The select, the ruler, the all-units table and the menu search all pick it up. No component is touched.

Develop

npm install
npm run dev       # http://localhost:5173/unithub/
npm test          # 115 tests — engine, formatting, URL round-trips, i18n coverage
npm run build     # tsc + vite → dist/
npm run preview   # serves the real build at :4173

Deploy

Static SPA behind nginx, served under the /unithub subpath, and the subpath is real inside the container — the container path matches the public path 1:1.

docker build -t unithub .
docker run -p 8080:80 unithub   # → http://localhost:8080/unithub/

On Dokploy: build from the Dockerfile, then set the domain to Host app.lucaskalil.com, Path /unithub, Strip Path = OFF, Container Port 80.

Strip Path = ON is the one setting that breaks this. Traefik would forward / and nginx would 404 every request.

The path is written in exactly one place — base in vite.config.ts. Everything else reads it back through import.meta.env.BASE_URL (src/lib/basePath.ts), so moving the app is a one-line change.

Deploys are manual from the Dokploy UI, by choice: nothing here needs to ship on every push.

Measured

Lighthouse against the live URL:

	Mobile	Desktop
Performance	98	100
Accessibility	100	100
Best Practices	100	100
SEO	100	100

Stack

React 19 · TypeScript · Vite · React Router · lucide-react · Vitest.

Fonts are self-hosted variable woff2 — Space Grotesk (display), Inter (UI), JetBrains Mono (numbers) — all OFL licensed. Linking them from Google cost 912 ms of render-blocking time and two third-party origins per visit.