About usepreciso DateTime
Date and time tools for developers and travellers.
What is this?
usepreciso DateTime is a collection of free utilities that run entirely inside your browser. There is no backend, no database, and no server processing any of the data you enter.
8 tools for working with time and timezones.
🔒 Privacy by default
In the age of AI, everything you paste into a browser tool is potential training data for someone. A JWT you decode, a private document you run a word count on, a JSON payload you format - most tools send that to a server. Some feed it into models.
We built usepreciso so that question never arises. Every calculation, conversion, and transformation happens locally in your browser using JavaScript. Nothing is transmitted. Nothing is stored. Nothing is logged.
The tools
Timezone Converter
Convert times across any timezone
World Clock
Live clocks on an interactive map
Age Calculator
Exact age with birthday countdown
Unix Timestamp
Convert timestamps to dates and back
Date Calculator
Add or subtract days, months, years
DST Tracker
68 countries, full historical data
Meeting Planner
Find overlap across timezones
How it's built
Eight independent Next.js 14 apps share a single npm workspaces monorepo, with a shared@usepreciso/utilspackage for all core logic. Each app is deployed separately to Firebase App Hosting on its own subdomain.
All processing uses native browser APIs - Web Crypto for hashing, Intl for date formatting, Canvas for image processing. No heavy libraries where a native API exists.
Got feedback?
Found a bug, have a feature idea, or just want to say hi? We'd love to hear from you.
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