The Ruby on Rails Gem you should not miss in 2021!

Tram Ho

In this post, I will introduce to you about the very reputable gems that are used the most by developers in 2021.

What is Gem?

Gem is a Ruby library. It is no different from the libraries of other common languages ​​like PHP, Java or Python but the library in Ruby is called GEM. Only that simple. And of course when we install rails, we will use this command:

It follows that: rails is also a gem!

The top Ruby gems that developers regularly use this year:


Can easily batch import records with activerecord import . This is a very fast and powerful ruby ​​gem, you don’t have to wait dozens of hours to import each record again. For usage, please refer here with 3.5K star rating


With hundreds of millions of downloads, Kaminari tops the list of most widely used and most popular ruby ​​gems. You can paginate anything even if it’s an array.

** GITHUB : 7.9K stars


Once you accidentally delete a record it can be very bad. Therefore, to remedy this, paranoia hides the record by specifying the query scope on the model. However, if you want to remove it completely, you need to use the Really_destroy function

** GITHUB : 2.6K stars

4: PaperTrial

You are often very annoyed with using undo and redo actions because of changes in your model. Gem PaperTrial helps you keep all changes by naming all revisions with every change and thus, working with your model is easy.

** GITHUB : 6K stars


This Gem makes it easy to add foreign languages ​​to your applications, that is, to adapt to internationalization. Globalize gem is powered by Google’s i18n API. This gem helps to translate non-static database content.

** GITHUB : 2K stars


State machines for Ruby classes. It sounds confusing at first glance, but this gem allows ruby ​​on rails developers to add finite states to their ruby ​​classes. It is a generic library that provides adapters for different ORMs.

** GITHUB : 4,3K stars


With Draper, developers can easily build decorators around models. Using Draper Gem in your Ruby on Rails Apps adds much cleaner views. There is no need to write helper with the Draper being used. Developers can easily define a draper instead of calling the traditional helper. It also provides a list of properties and extension methods for the object.

** GITHUB : 4,9k stars

8: Single Form

The name tell everythings. Simple Form allows you to use forms in your rails application with clean and efficient code. It offers exceptional flexibility when working with form elements such as checklists, radio buttons, drop-down lists, etc.

** GITHUB : 7,8K stars

9: Meta Tags

This gem helps you create SEO friendly apps by following SEO best practices and creating effective meta tags.

** GITHUB : 2,4K stars

10: SLIM

If you use this interesting gem you will enjoy the fun feeling when coding html but code css

** GITHUB : 5k stars

11: HAML

This gem stands for HTML Abstraction Markup Language. Developers use it to enhance the structure and design of their HTML / XML documents.

** GITHUB : 3.6k stars

12: PRY

Developers often face library integration problems or difficulty in binding gems while coding. During that time, they have to deal with a lot of errors. For getting rid of these problems and debugging, the PRY rails gem turns out to be an ideal choice. This gem allows you to set breakpoints and perform step-by-step code debugging. Pry comes with a unique set of features, including syntax highlighting, run-time calling, command shell integration, Exotic object support, and a powerful and flexible command system.

** GITHUB : 6.2k stars

13: Better Errors

When your users encounter an unattractive error page, they can abandon your application. Better error pages will replace clumsy and disavow RoR error pages with rather improved and better error pages.

** GITHUB : 6.7k stars

14: Binding of Caller

The Gem above helps your users have better user experience but found no reason behind the error. Here, this gem allows to find variables that lead to app crashes.

** GITHUB : 616 stars


Gem RSPEC RAILS is a perfect choice for developers who want to write unit test cases. This Gem facilitates the application to integrate the RSpec framework into any Rails project. User just needs to create the necessary configuration files and help specifications. The framework is used in TDD and BDD environments. In a nutshell, the RSPEC RAILS installer gem features a neat description and syntax.

** GITHUB : 4.5k stars

16: Letter Opener

This gem allows you to see previews of messages your Rails application sends – on your browser screen. It makes it easy to check and edit in your inbox.

** GITHUB : 3.2k stars

17: Capybara

Gem integrates tests to help users by guiding them through the ongoing process in short phrases. Developers use it most of the time in authorization scenarios. Capybara is often used together with the RSPEC gem.

** GITHUB : 9,3k stars

18: Database Cleaner

This gem wipes your test database, and you can set a cleanup time – before launching the test or before and after running it. It is supported for Ruby versions 1.9+.

** GITHUB : 2.7k stars

19: Factory_Girl

Gem factory_girl provides dummy data for test cases. This helps ease your testing process as you don’t have to enter data manually every time.

** GITHUB : 2k stars

20: Shoulda_Matchers

This amazing gem writes a single line validation / link test that is compatible with Rspec. You can quickly test your application’s functionality really quickly using combos.

** GITHUB : 3k stars

21: SimpleCov

This gem measures coverage for your unit test

** GITHUB : 4,2k stars

22: Rails_Controller_Testing

Support writing unit tests for controllers

** GITHUB : 229 stars


CANCANCAN Gem is perfect for developing complex applications. It allows a user to have multiple permissions, but needs to restrict access to certain users. This gem makes it easy to set user access restrictions and everything is manageable in one place.

** GITHUB : 4.8k stars


When creating an app on any social network or building an e-commerce solution, users often need to log into the social media page. It will need to provide authorization and authentication for the specific application. Some people use their code for different purposes; Others prefer to use this gem for authentication. DEVISE Gem turns out to be one of the best ruby ​​gems of 2021. It makes the job efficient and easy. DEVISE consists of 10 modules. However, the unoptimized URLs of the website must be dealt with. FriendlyId easily converts URLs into much more memorable and friendly website URLs. The best part is that it doesn’t require any code modifications in the web application, making it a well known Ruby gem.

** GITHUB : 21.6k stars

25: OmniAuth

This is a gem that supports devise for 3rd party login like google, facebook, …

** GITHUB : 7,4k stars

26: Ruby-JWT

Support confirmed JWT

** GITHUB : 3k stars

27: Rolify

Rolify is a role management gem that doesn’t enforce any scope of support on the resource object.

** GITHUB : 2,8k stars

28: activeadmin

This framework is used to build the interfaces of the administrative style. Active Admin summarizes business application patterns and makes it easier for developers to implement sleek and elegant interfaces with less effort. Its various features include Scope, User Authentication, General Navigation, Action Item, Sidebar Section, Index Style, Filter, Downloads, and APIS.

** GITHUB : 8,9k stars

29: Rubocop

You want to write standard code only? Let’s use rubocop

30: Sidekiq

Sidkiq is the standard clean and efficient background job tool used to handle Ruby. Especially for scheduled jobs Sidekiq is used. The Redis library supports this gem and it uses Redis as a task manager. Sidekiq has succeeded in impressing a large number of developers because of its multithreading capabilities. Possessing these capabilities, the use of Sidekiq brings a considerable speed. Significant benefit of using this gem involves monitoring work properly. Proper handling of states and opportunities for parallel work. While Sidekiq doesn’t need Rails, it integrates with Rails to clarify and easily handle the background to a great extent.

** GITHUB : 10.8k stars

I wish you a productive day!

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Source : Viblo