Assembly Line

Day.js

⏰ Day.js 2kB immutable date-time library alternative to Moment.js with the same modern API

Day.js is an open-source libraries and runtimes project on GitHub under the MIT license (permissive), with 49k stars. It is built with V8. Its last push was 2 months ago.

Stars
49k
License
MIT
Activity
Active
Latest release
v1.11.23

Code on GitHub Website

Judgement

What it is
Building block
What it does
A 2 kB immutable date library with an API almost identical to Moment.js, extended through plugins for time zones, relative time and more.
Adopt it when
You are replacing Moment.js and want the smallest change to existing code, or need a tiny date library in the browser.
Watch out
Time zone and many other features are plugins with known edge-case bugs, and development has slowed.
Ready for
Production-ready
Runs as
Library
Built with
JavaScript
How established
Established: started 8 years ago, latest release v1.11.23.
What the license allows
You can build it into a product you sell, as long as you keep its copyright notice.

Judged on 2026-11-06 from the project's README and GitHub data. The license and age lines are worked out directly.

Built from

V8

Follow it down: Day.js → V8 → LLVM project → runs on a microchip

How compilers were built, back to punched paper tape

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Stars, license and activity come from GitHub and refresh on a rolling hourly schedule. The project's own description is quoted as written.