Create your own Jekyll theme gem


Dr. Jekyll reading in the laboratory

Why create your own theme gem?

Creating your own Jekyll theme gem is awesome for several reasons:

• Jekyll is an open-source platform where you can learn from others, and your own creation may inspire the next person to take the torch and create something great of their own.

• You will learn a ton in the process, including how to publish a gem.

• You can customize and make your theme exactly how you’d like it to be.

• That all goes without saying that it’s an excellent way to show off your coding chops.

Planning your creation

Now that you’re sold on creating your own Jekyll theme gem, let’s dive into the first consideration: what do you want to do? You don’t have to know right away, but it helps to have some idea of what you want to accomplish. Take a look at a lot of other Jekyll themes and see what you like, what you don’t like, and maybe you’ll have some new ideas that you’re not really seeing out in the wild. For instance, I didn’t like that you couldn’t paginate within a specific group of tags, and I didn’t see many examples out there that had this functionality, so I made that a goal of mine. A couple of great places to look at themes are the awesome-jekyll-themes GitHub page, and the Jekyll Themes site.

You should also try downloading several different gem-based themes and notice how easy is it to setup? How easy it to configure? Being able to get up and running quickly with a new theme is an important consideration. Although I am really proud of the jekyll-theme-collider gem I created, there are quite a few steps to get up and running.

A lot of this is due to the fact that I was using the jekyll-paginate-v2 plugin, which requires an unconventional folder structure. Other customizations I made contributed to this as well. The pagination plugin I used also made my theme unavailable for use on GitHub Pages. So just beware that the more you stray from the conventions of Jekyll, the more complicated your setup may be. Notice how that in most gem-based themes, it is only the assets, _layouts, _includes, and _sass directories that are included in the gem. Any other custom files or folders you add will make the theme harder to setup. If you haven’t already, make sure to give this Jekyll docs page on themes a good look before you begin.

Now that we’ve gone over all of these considerations, lets take a look at the nitty gritty of how to create your own theme.

Dr. Jekyll smoking in the laboratory PS you probably shouldn’t smoke in the laboratory…

How to create your gem-based theme

To create a new Jekyll scaffold for your gem theme, simply run:

  jekyll new-theme jekyll-theme-awesome

This will create many files and folders for you to base your theme on. The jekyll-theme-awesome.gemspec file that will be created is important to publishing your gem, so make sure to fill out all the required info there. You will at the very least need to change the spec.summary and spec.homepage values in order for you to successfully run the bundle exec jekyll serve --watch command.

The gemspec file is where all the important information for your gem lives, including the author name, version number, and what dependencies the gem has (such as plugins). The spec.files line is where you say what files should be included in the gem. You can edit this, but it definitely goes against the conventions of Jekyll. The conventional nature of Jekyll is what makes it so easy to use, so just be aware of this if you choose to edit this line. In this line you can see that by default the assets, _layouts, _includes, _sass, LICENSE.txt and files and folders are all included in your gem.

If plugins are required in order for your theme to work, you will need to add each plugin in this file like so:

  spec.add_runtime_dependency "jekyll-paginate-v2", "~> 1.7"

File structure overview

As a quick refresher, here’s what all the other files and folders that were created are for:

  • The _includes folder is for reusable partials that you may want to include throughout your theme.

  • The _layouts folder where you keep the main template files, such as the default post layout.

  • The assets folder is where you’ll keep any images, graphics, etc that you’ll want to include in your gem. This is also where you’ll import your Sass files. For instance, inside this folder I have a css folder with main.scss inside. In this file you’d simply include the following:

@import "jekyll-theme-awesome";

  • The _sass folder is where your style partials will go. And if you setup your css as above in the assets folder, you’d place your jekyll-theme-awesome.scss file here, and then import whatever other Sass partials you’d like here. You’ll also need to include this in your config.yml so that Jekyll knows where to pull in your Sass partials:

    sass_dir: _sass

  • The Gemfile will simply point to your .gemspec file, and is where Bundler looks to manage your gems.

  • The is where you’ll provide the documentation for your theme, including how to install and configure the gem.

  • The LICENSE.txt is where you state what kind of license your theme falls under. By default it is set to be under the MIT license.

Begin theming

Without having done anything but edit the .gemspec file’s spec.summary and spec.homepage configuration, you could run the bundle exec jekyll serve --watch command, head to localhost:4000 in your browser, and you wouldn’t see much but an index of your site directory. You can add an index.html file to your root directory and add something like the following to see something slightly more interesting:

title: Home
layout: default
# Yello?

So now you can really go crazy and start to make your theme. Give some style to your _layouts/post.html template, create some example posts with lots of varied content so you prepare your theme for all the various use cases. Add pagination, add tags, create an about page. Add lots of styling. Go nuts.

Create a config file

Another thing you’ll really want to do is create an example config.yml file, because you can make it really quick and easy for someone downloading your gem to get setup. For example, here is part of the config.yml file I created for the gem theme I created:

title: Rando Dev
description: >
  This is the Collider Jekyll Theme.
baseurl: ""
url: ""
hosted_url: ""
github_username: ""
linked_in_profile: ""
full_name: Rando Dev
user_description: Software Engineer
  shortname: jekyll-theme-collider-netlify-com

Instead of someone having to track down and edit every partial where their name is displayed in your theme, they can simply edit the full_name line. That would allow you to do something like this in one of your layouts:


Any of the config.yml variables are available throughout your site using the {{site.variable_name}} convention.

Publishing your gem

Once you’ve done all the cool things you’ve wanted to do with your theme and feel it is ready to be published, sign up for an account at

Then you’ll build the gem using this command:

  gem build jekyll-theme-awesome.gemspec

After you run this, a file will appear in your root directory that will look like this:


To push up and publish your theme, you’ll use this command:

  gem push my-theme-0.1.0.gem

You will be prompted to sign in with your credentials, and once you do so your gem will be published!

Way to go. Pat yourself on the back. 🎉

Testing and documentation

Now it’s time to give your gem some good testing. Try downloading your theme to a new Jekyll project. How easy is it to setup and configure? Do you run into any snags? Take notes as you go through each step installing and configuring your theme. This brings me to my next topic (read: rant), documentation.

As an English major who values good communication, I take these things seriously. Why go through all the work of creating an awesome theme while leaving your potential users without a clue how to use it? Really come from the perspective of someone who knows very little about Jekyll or coding at all (ok maybe not that far, but you get the idea). Take nothing for granted. Assume they run into every possible issue while attempting to setup your theme and won’t magically know where to look for your theme’s more eccentric features.

So now you’ve tested your theme and created awesome documentation, good on you 👏. But naturally, you want to continue adding to and developing your theme even further.

Publishing your next gem version

Once you’ve created your next round of changes and want to push it up to your gem, use the following steps:

  • In your .gemspec file, change the spec.version configuration to the desired version number. Use this guide from to help determine what your version number should be.

  • Then run the gem build jekyll-theme-awesome.gemspec command again to build the next version of your gem.

  • To push up your new gem version, run this command as before, but with your new version number at the end, like so:

  gem push my-theme-0.1.1.gem

That’s all there is to it.

And since this may be the first of many gem versions you publish, I’d recommend creating a file to highlight what has changed with each release. Take a look at this site for more info on changelogs.


Amazing, you’ve now created your very own Jekyll gem theme! It’s a great feeling to contribute to open-source and have a bundle of code out there that you created and someone can possibly benefit from. Please contact me or comment below if you have any questions about this article or how to create your own gem theme, I’m happy to help!