How do you extend Jekyll with the plugins folder

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Extending Jekyll with the _plugins folder is one of the most effective ways to customize your static site beyond the default features. Many beginners on GitHub Pages are unaware that Jekyll supports custom plugins, filters, and generators. This article will guide you through the basics of using the plugins folder, practical examples, common mistakes, and long-term benefits for your site’s workflow.

Comprehensive Guide to Jekyll Plugins

What are Jekyll plugins

Jekyll plugins are Ruby scripts that extend the functionality of your site. They allow you to go beyond the default markdown and Liquid features by introducing custom filters, tags, generators, and hooks. With plugins, you can automate tasks, process data, or create new behaviors that Jekyll does not support out of the box.

For example, if you want to add a custom date format, build a tag cloud, or fetch data from external files, plugins can help. They are essentially small Ruby programs that Jekyll runs during the site build process.

Creating the plugins folder

To use plugins, you must create a folder named _plugins in the root of your Jekyll project. Inside this folder, you place Ruby files with the extension .rb. Jekyll automatically loads these files when building your site locally.

_plugins/
  custom_filter.rb
  generator_example.rb

Each plugin file can define one or more functions. These functions can extend Liquid with filters or tags, or modify how Jekyll processes your content. The key benefit is that you do not need to publish these scripts separately—Jekyll detects and runs them automatically.

Writing simple plugins

A good starting point is to write a filter plugin. Filters modify the output of variables in your Liquid templates. For example, if you want a custom filter to reverse text, you can create a file named custom_filter.rb inside _plugins:

module Jekyll
  module CustomFilter
    def reverse_text(input)
      input.reverse
    end
  end
end

Liquid::Template.register_filter(Jekyll::CustomFilter)

You can then use this filter inside your markdown or HTML templates like this:

{{ "Jekyll Plugins" | reverse_text }}

This will output sngulP llykeJ. While this is a simple example, it demonstrates how easy it is to expand Jekyll’s capabilities.

Using custom filters

Custom filters are among the most popular uses of plugins. They help you format text, process data, or even handle conditional output. Here are some practical use cases:

  • Formatting dates in a specific way not supported by default.
  • Generating excerpts with character limits.
  • Transforming tags into SEO-friendly slugs.
  • Sanitizing user-generated content before rendering.

By placing these filters in _plugins, you centralize your custom logic and avoid repeating code across templates.

Understanding GitHub Pages limitations

One important detail: GitHub Pages does not allow arbitrary plugins for security reasons. This means that custom plugins in _plugins will not run when your site is built directly on GitHub’s servers. Instead, you must use one of two approaches:

  1. Build locally: Run jekyll build or bundle exec jekyll build on your computer and push the generated _site folder to GitHub.
  2. Use GitHub Actions: Configure a workflow to build your Jekyll site with plugins enabled and deploy the result automatically.

This limitation is often confusing for beginners, but once you set up a workflow, it becomes seamless. For those who want a plugin-heavy site, GitHub Actions is usually the best long-term solution.

Workflow benefits of plugins

Using plugins can save time and simplify your site management. Some benefits include:

  • Automation: Generate content automatically, such as tag pages or sitemaps.
  • Consistency: Apply formatting rules across all posts without manual editing.
  • Flexibility: Add site-specific features without waiting for official Jekyll updates.

For example, you could create a plugin to automatically insert schema markup into every blog post, improving your SEO without manual intervention.

Common mistakes to avoid

While plugins are powerful, there are common mistakes beginners should avoid:

  • Expecting custom plugins to run automatically on GitHub Pages without local builds or actions.
  • Placing plugin files in the wrong directory or forgetting the .rb extension.
  • Writing inefficient code that slows down site builds.
  • Not testing plugins locally before deploying.

A disciplined approach to plugins ensures they remain an asset rather than a source of errors.

Examples of practical plugins

Here are some ideas for practical plugins you can create:

Plugin Idea Purpose
Word Count Filter Calculate the number of words in a post for reading time estimates.
Slugify Filter Turn post titles into SEO-friendly slugs automatically.
Custom Excerpt Generator Create excerpts of consistent length across posts.
Related Posts Generator Automatically generate related content links based on tags.

These examples show how even small scripts can dramatically improve the user experience of your site.

Frequently asked questions

Can I share my plugins with others?

Yes, you can package plugins as Ruby gems and publish them for the Jekyll community. This allows others to install them via Gemfile.

What happens if my plugin breaks?

If a plugin introduces errors, Jekyll will usually display the issue in your terminal during build. Always test locally and keep backups of your site before adding new plugins.

Are plugins safe to use?

Yes, but only use trusted sources or write your own. Avoid copying unverified scripts from the internet to prevent security risks.

Final thoughts and next steps

The _plugins folder gives Jekyll users enormous power to shape their site’s behavior and design. While GitHub Pages imposes restrictions, you can still unlock advanced functionality through local builds or GitHub Actions. Whether you need custom filters, generators, or simple automations, plugins help you save time and enhance your content workflow.

Call to action: Create a small plugin today, such as a custom filter, and test it locally. You will see how quickly plugins can elevate your Jekyll blogging experience.