Moment.js is Officially Deprecated: What Developers Should Know in 2025

Moment.js, the once-essential JavaScript library for handling dates and times, has officially been deprecated. For many developers, this news may come as no surprise, as Moment.js has been marked as a “legacy project” since 2020. But if you’re still using it, now’s the time to consider upgrading to more modern and efficient libraries.

Whether you’re familiar with the deprecation or hearing about it for the first time, here’s what you need to know about why Moment.js has been phased out—and which tools you can use instead.

Why was Moment.js So Popular?

Moment.js first made its mark in 2011 by simplifying the headache of working with JavaScript Date objects. Before Moment.js, parsing, formatting, and manipulating dates in JavaScript was a major challenge. The library’s intuitive API and powerful features quickly made it the go-to date handling tool, especially for large projects.

By 2020, Moment.js had become one of the most downloaded libraries on NPM, with over 15 million weekly downloads. However, as technology evolved, the JavaScript community began to recognize some significant limitations.

Why is Moment.js Deprecated?

Moment.js served the community well for years, but it was designed in a way that eventually became outdated for modern JavaScript needs. Here’s why the team decided to officially stop development:

1. Large File Size: Moment.js is a heavyweight, weighing in at around 67KB minified and 284KB uncompressed. This is considerably large, especially for performance-focused projects where smaller libraries are ideal.
2. Mutable API: Moment.js uses a mutable API, which means it modifies the original date object when making changes. This often causes bugs and unexpected side effects, especially in complex applications where immutability is preferred.
3. Timezone Handling: Although Moment.js offered a separate moment-timezone library, it wasn’t an integrated part of the core library and added more complexity.
4. Outdated Design: The Moment.js API was developed before JavaScript introduced modern features like ES6 and Intl, which is now the standard for localization and date formatting. Additionally, the upcoming Temporal API promises even more date-handling capabilities.

In September 2020, the Moment.js team made the difficult decision to officially deprecate the library, putting it into maintenance-only mode. This means that while critical bugs and security issues will be patched, no new features or improvements will be added.

Why Isn’t Moment.js Marked Deprecated on NPM?

Many developers are surprised to find that Moment.js doesn’t display a “deprecated” label on NPM. This is because it’s still in long-term maintenance mode, receiving essential updates as needed. The Moment.js team wanted to support developers by providing stability for existing projects, so while no new features will come, Moment.js is still stable and usable.

What are the Best Alternatives to Moment.js?

With Moment.js moving into legacy status, several modern alternatives are lighter, faster, and better suited for current JavaScript standards. Here are some of the top options:

1.Day.js

• File Size: At just 2KB, Day.js is a highly compact option.
• Similar API: Day.js’s API closely mirrors Moment.js, making it one of the easiest options for developers looking for a near-drop-in replacement.
• Immutable by Default: Day.js uses immutable data structures, which prevents unintended mutations and helps with debugging.

2. Luxon

• Developed by the Moment.js Team: Created by the same developers, Luxon was designed with a modern JavaScript mindset.
• Native Support for Timezones and Localization: Luxon offers first-class timezone and localization support, which was always a struggle with Moment.js.
• Built on Modern JavaScript: Luxon takes advantage of the Intl API, making it more efficient and future-proof for JavaScript developers.

3. Date-Fns

• Modular and Lightweight: Unlike Moment.js, date-fns is modular, allowing you to only import the functions you need, which helps keep your bundle size small.
• Functional API: date-fns embraces functional programming and has an immutable approach, which makes it easier to manage state in complex applications.
• Comprehensive Function Library: date-fns provides a wide range of functions for all types of date operations.

4. Native JavaScript Date

• JavaScript itself has made strides in date handling with tools like Intl.DateTimeFormat for formatting dates in various locales, and the upcoming Temporal API, which will add powerful, native date manipulation capabilities.

Related read: Exploring JavaScript Date Library: Date-Fns vs. Moment.js

What Should You Do if You’re Still Using Moment.js?

If you’re maintaining a project that uses Moment.js, there’s no immediate rush to replace it. The library is still functional and will receive important security and bug fixes. However, for any new projects or major updates, it’s recommended to switch to a more modern alternative like Day.js, Luxon, or date-fns.

The Future of Date and Time in JavaScript

For those who have relied on Moment.js, it may feel like the end of an era. But with new libraries and JavaScript itself evolving, developers now have access to faster, more efficient ways to handle dates and times. Moment.js played a significant role in shaping JavaScript date handling, but as the web continues to evolve, we have plenty of tools to step into the future.

Whether you go with Day.js, Luxon, or date-fns, upgrading will allow you to take full advantage of modern JavaScript standards and performance improvements.