Comparing
Modern JavaScript date utility library
2KB immutable date time library alternative to Moment.js with the same modern API
| Metric | date-fns | dayjs |
|---|---|---|
| Ecosystem | npm | npm |
| Difficulty | Intermediate | Intermediate |
| Weekly downloads | 71.4M↑ | 43.9M |
| Latest version | v4.1.0 | v1.11.20 |
| Recipes | 2↑ | 1 |
date-fns only
Shared
dayjs only
Use date-fns for formatting, parsing, arithmetic (add/subtract days, months, years), comparison, and locale-aware output in any JavaScript environment. Import only what you need and the bundle impact is minimal.
Use Day.js when you need date parsing, formatting, arithmetic (add/subtract days/months), or comparisons in browser code where bundle size matters. Its plugin system covers timezones, relative time ('3 hours ago'), duration, and ISO weeks.
date-fns v2 has limited first-party timezone support — for complex timezone-aware applications use Luxon or the Temporal polyfill. The function-heavy API can feel verbose for simple one-liners; Day.js's method chaining is more readable in those cases.
For complex timezone-aware calendar applications, consider Temporal (the upcoming TC39 proposal) or date-fns with explicit timezone handling. Day.js's plugin system can grow large if you need many features.
date-fns
dayjs