So, you have a site that currently consists of one or more HTML files, and maybe some images. Your site is growing, and you're starting to think that using a template engine might be nice so you can write your pages in Markdown, or share your meta tags and layout between multiple pages. You know about Eleventy, and have maybe dabbled in using it for a blog before using a starter project. But how the heck do you start using Eleventy on a simple HTML site that already exists, without adding a lot of extra stuff you don't need?

# Setting Up Eleventy

For this post, I'm assuming you already have node and npm installed on your machine.

  1. Add a package.json

    • Run npm init in your site's working directory to create a package.json file, where metadata about your project and a list of dependencies will be stored. Go through the interactive prompts and set the metadata as accurately as you want; you can always change them later.
      remove the main key from the package.json that was just created.
  2. Install Eleventy into package.json

    • Run npm install --save-dev @11ty/eleventy
    • Add these entries to your package.json scripts:
"scripts": {
"build": "npx @11ty/eleventy",
"start": "npx @11ty/eleventy --serve",
"debug": "DEBUG=* npx @11ty/eleventy"
  1. Add a .gitignore
    • Your site has node_modules/ now where it didn't before, so you may need to add a .gitignore file if you haven't already. Here's what I keep in the .gitignore for this site:
  1. If your site has a readme, make Eleventy ignore it.

    • Add a file in the root of your project directory called .eleventyignore and add the name of your readme there. (perhaps
  2. Run npm start and hope for the best
    You should see a few files being written to the _site directory - hopefully the files that make up your site and nothing else.

    • Common issues:
      • Your readme is being transformed by Eleventy and written to _site - maybe it even throws an error.
        Solution: make sure you completed step 4.
      • Eleventy is trying to process things in node_modules, and throwing errors.
        Solution: make sure you added a .gitignore, and included node_modules/ in it. If you don't want to gitignore your modules, add node_modules/ to your .eleventyignore file.
      • Start script is missing - see step 2 for how this script should be defined in your package.json. If you run npx @11ty/eleventy --serve directly, it may appear to work now, but the .eleventyignore and .eleventy.js files we're going to add won't get read.
      • Your CSS or images are missing when you load the site in a browser.
        Solution: We'll tackle that next.
  3. Make sure your assets are getting written to _site.

    • By default, html files will get written to the build output directory (_site), but your CSS files and images won't be. To address that, we'll need to add an Eleventy config file and configure it to write your assets to the build directory.
    • Add a file named .eleventy.js (the leading . is important!)

The most basic structure of an .eleventy.js file looks like this:

module.exports = function(eleventyConfig) {
// call functions on eleventyConfig here

// return object options in the object starting on the line below
return {};

Set a passthrough file copy for your images, CSS, and any other files you need to be in the final site but don't need Eleventy to process, like PDFs, by adding these lines, replacing the arguments to each addPassthroughCopy call with the names of the directories where those assets are stored in your project, or a file-selecting glob. (See the docs on passthrough file copy for more details on this.)

module.exports = function(eleventyConfig) {
// call functions on eleventyConfig here

// return object options in the object starting on the line below
return {};

# Deployment

The instructions here assume you're using Netlify for hosting - the steps you need to take my differ if you're using a different hosting provider.

Since my site is already live, I want to convert it to serve from _site without any downtime. When it was just html files, my only build command was to rm and then serve everything that was left in my repo. With Eleventy, I want Netlify to build the site, then serve only what's in _site.

To make this happen without any downtime, I'm going to add a netlify.toml file with deploy instructions so that nothing changes until this branch with all the Eleventy stuff goes into the main branch of my site. There is probably a way to do this through the Netlify UI, maybe involving stopping builds for a time, changing settings, and then re-activating, but this feels easy enough for now and means that the Netlify deploy previews on PRs that I have turned on will work for this Eleventy conversion work.

Add a file called netlify.toml and put this in it:

  publish = "_site/"

  command = "eleventy"

# Next Steps

At this point, you should have a working Eleventy site - if you're missing files, take another look at your passthrough copy configurations. You can start using any of the template formats supported by Eleventy by default for new pages, or convert existing pages to use them.

For your files with an .html extension, you can start adding liquid syntax right away. Or, you can change the htmlTemplateEngine to your template engine of choice (I like nunjucks) and use that in your html files. You can make this change gradually and incrementally, adding just the templating that you need without converting your whole page to use that language.

# Adding layouts

By default, Eleventy will look for layouts in the _includes directory. If you want to create a layout for multiple pages to use, create a layout at _includes/base.njk (replacing base with whatever you'd like your layout to be), and copy over any layout-related HTML boilerplate from your original HTML page to that file. (by 'layout', here I'm referring to things like the HTML doctype declaration and the root html, head, and body tags and anything that's shared across pages in head, not the layout of the content of an individual page.)

Your layout file might look something like this snippet taken from the Eleventy docs on layouts.

title: My Rad Blog

<!doctype html>
<html lang="en">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Converting a simple HTML site to use Eleventy</title>


Then, in the pages where you want to use this layout, add some frontmatter at the top of the file, like this:

title: Words to Override the Default Title from Layout
layout: base.njk

# Organizing Files

At this point your directory structure might feel a little messy - you've got config files nestled up against website files and the _site and node_modules directories. Perhaps you want all your website files in the same folder.

  1. Create a new folder; I called mine src
  2. Move the website-related files into it:
    • the whole _includes directory,
    • your html and css files,
    • and any other files that are being passed through to the build directory
  3. In your .eleventy.js file, modify the return value's setting for dir.input (note the dir!) so that Eleventy knows to look in src/ for all your files.

At this point, my Eleventy config looks like this:

module.exports = function (eleventyConfig) {
  // call functions on eleventyConfig here

  // return object options in the object starting on the line below
  return {
    htmlTemplateEngine: "njk",
    markdownTemplateEngine: "njk",
    dir: {
      input: "src",

# Conclusion

By now you should have a working Eleventy site with some basic file organization and all your existing code working the way it did before. Time to get back to writing content! (I know, you were probably doing this conversion to avoid that part.) Happy hacking!