dayte

A day-friendly library for business dates.

Most business logic thinks in calendar days — invoices, deadlines, bookings, birthdays — not in instants. Existing datetime libraries centre on timestamps and timezones, which makes day-level work awkward.

dayte treats the calendar day as the fundamental unit. It handles business dates, not timestamps: there is no time of day and no timezone, and every date covers an inclusive wyndow of days — a bare year like 2025 covers the wyndow from 2025-01-01 to 2025-12-31.

It borrows a small subset of EDTF (Extended Date/Time Format) syntax — calendar dates, masked digits (X), and intervals (/) — but not uncertainty, seasons, or sets. Every date has a canonical string form and round-trips losslessly, so it drops straight into JSON.

Packages

• Python — dayte on PyPI
• TypeScript — dayte on npm

Pre-release: nothing is published yet. Both packages are under active development.

Source, issues, and discussion: github.com/cactus-bm/dayte