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The most popular Ruby Gems in 2021

Are you a Ruby on Rails developer looking for the right gems to accelerate the development of your app? Check this list of the most popular Ruby Gems in 2021.

The most popular Ruby Gems in 2021

Are you a Ruby on Rails developer looking for the best and the most popular Ruby Gems to accelerate the launch of your app? At Forest Admin, quite a big part of our team works with Rails on a daily basis, so we decided to make your life easier by publishing helpful resources. We’ve already covered Rails Migrations, and the reasons to choose Ruby on Rails.

This article gathers the most popular Ruby Gems in 2021. Let’s get started!

As you most likely already know, Ruby Gems are package managers developed in ruby that facilitate and accelerate processes like app creation, deployment, library support, API connection, etc.

Ruby Gems are open source, and you can find them on RubyGems.org.

Authentication and Authorization

Devise is one of the most widely used gems, downloaded almost 105 million times. It is a library that offers authentication services, and it owns its popularity to the simplicity of use and good support.

Pundit helps to define authorization systems that ensure that users are allowed access they are supposed to have or to perform an action they are supposed to perform.

Devise Invitable is an add-on gem that allows users to invite others to the application. It is commonly used in SaaS products.

OmniAuth is another highly popular gem among developers building SaaS applications as it allows users to log in using their Facebook or LinkedIn accounts.


Pry-byebug combines Pry and Byebug gems and extends the functionalities of both. Thanks to this popular Ruby gem, you can set console breakpoints and implement step-by-step code debugging of each piece of code between these breakpoints.

Better_errors provides an alternative error page for Rails Applications. It also includes the source code inspection.

An editor showing a Ruby-on-Rails agent override.

Ransack is a popular gem, the successor to the MetaSearch gem, that allows for creating simple but robust search forms.

Simple Form is another gem that implements simple and easy to use DSL for building forms, which saves time that otherwise would be spent on writing forms in HTML.

Elasticsearch gem is often the first choice for developers who want to include a built-in search functionality. It is particularly appreciated in e-commerce as it allows for indexing catalogs of products, storing transaction information, and facilitating data analysis with dashboards.


Active Merchant, created and maintained by engineers from Shopify, allows for integrating 145 (!) payment gateways thanks to a centralized API.

Stripe gem interacts with Stripe.com — one of the most popular payment gateways, heavily used by e-commerce businesses. Forest Admin has a Stripe integration as well.


BrakeMan is a security analysis tool that scans the application for security anomalies.

Bundler reduces an application’s dependencies by tracking and installing the exact gems and versions that are necessary. It also helps to make sure that gems are present in development, staging, and production environments.

Lockbox is a gem that provides modern encryption. Lots of Ruby on Rails developers are choosing it thanks to its many integrations and zero dependencies.


RSpec is commonly used to create tests, especially in BDD and TDD environments. Users like its effectiveness, clear syntax, and being able to write tests as closely to “human” language as possible.

Capybara automates a user’s interactions in a browser, such as filing a form, finalizing a purchase, clicking on buttons, etc.

Faker is another useful gem that generates fake names, phone numbers, addresses, and other data. Thanks to this, you can quickly build and test an application before filling it with real data.

Admin Panel and other Internal Tools

Active Admin is a popular admin panel solution for customer-facing Rails applications. It is a reliable and 100% free option for smaller projects that require a high level of customization.

Forest Admin is a highly secure Active Admin alternative that is designed to scale. It offers similar functionalities (managing the website, search, data visualization and analytics, permission management, etc.) but much more flexibility thanks to Smart Actions and the powerful UI. With Forest Admin, even non-technical teams, like sales or customer support, can easily adapt the internal tool to their needs and business logic. Developers, on the other hand, are not restricted by the tool but they’re able to implement even very complex and unique features.

A dashboard in the editor mode of the Forest Admin UI.
A dashboard in the editor mode of the Forest Admin UI.

Read the detailed comparison of Active Admin and Forest Admin.

Read how Raspberry Pi uses Forest Admin on top of their Rails application.

Ruby on Rails developers would struggle a lot without gems. They accelerate software development and also play a vital role in solving common problems like authentication and authorization, testing, debugging, and ensuring high security. Gems are not a silver bullet and they won’t replace skilled developers, however, in most cases where there is no need to reinvent the wheel, as gems make software development faster and more efficient on their own.


If you are looking for an internal tool solution for your Ruby on Rails application, try Forest Admin for free as an Active Admin alternative.