About heyutil
Fast, private business utilities that run entirely in your browser.
Why it exists
Most online calculators are slow, ad-heavy and quietly send your data to a server. heyutil is the opposite: 52 focused tools that load instantly, work offline, keep your inputs on your device, and never ask you to sign up.
Principles
- Local-first. Calculations happen in your browser. Favourites, recents and last inputs live in
localStorage. - Keyboard-first. Press / or Ctrl/⌘+K for the command palette, ? for shortcuts.
- Honest data. Live rates and CPI readings show their source and date, and fall back to clearly labelled snapshots.
- No dark patterns. No ads, no tracking pixels, no accounts.
How it is built
- Plain HTML, CSS and JavaScript — no framework, no build step for the UI.
tools.jsonis the single source of truth; a build script generates the per-tool pages, category pages, sitemap,llms.txtand social cards.- A Cloudflare Pages Function proxies the currency rate table; everything else runs client-side.
- Installable as a PWA and usable offline via a service worker.
- QR codes and YAML conversion use bundled MIT libraries; translation uses MyMemory.
Install
Use the install app button in the sidebar (or your browser's install option) to add heyutil to your device. It works offline afterwards.
Source
heyutil is open source: github.com/alpofreely/heydata_website. Bug reports and tool requests are welcome in the issue tracker.