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Creating and Using Eleventy Collections

Posted on: Nov 11, 2021 by Stephanie Eckles
🍿 6 min. read

Collections allow you to group templates and then sort, filter, and perform other manipulations to customize the display of your template content and data.

What Are Collections?

Collections are groups of template* content.

One template can belong to multiple collections. These collections allow you to sort, filter, and perform other manipulations to customize the display of your template data.

Learning all the ways to create collections provides you architectural freedom in creating your Eleventy site!

* In 11ty terms, a template is any content file to be processed or rendered by 11ty. If you create a new Markdown file, you have created a new Markdown template, etc.

Creating Collections

Collections are most often created from tags, but can also be groups based on other features like file type or front matter data. They can even be created from local data.

Collections From tags

The simplest way to create a collection is with tags, and there are four syntaxes available.

Single tag:

tags: cat

Multi-word tag:

tags: cat and dog

Multiple tags, single line:

tags: ['cat', 'dog']

Multiple tags, multiple lines:

- cat
- dog

Assigning tags to many templates

While the examples shown are intended to be placed in a single template's front matter, there is an alternate way.

You may create a directory data file to assign tags to an entire directory of templates.

Given a directory called posts, create the file posts.json (the name must match the directory name) and add the following to assign your tags.

// posts/posts.json

"tags": "posts"

Display Collection Data

Once you have several templates assigned to a collection - for example, blog posts - you may want to display some of the collection data.

This example works for both Nunjucks or Liquid templates and will output the name of each item in the posts collection:

{% for post in collections.posts %}
<li>{{ }}</li>
{% endfor %}

Other data available to display from a collection includes the following, as described on the 11ty Docs page for Collections:

More Ways to Create Collections With addCollection

Let's look at the options available for creating collections beyond tags. These will be created within our .eleventy.js config, and use the addCollection function. This function allows us to create either new or modified collections.

Group Tags Together

To create a collection based on multiple tags, use the additional function of getFilteredByTags.

eleventyConfig.addCollection("tagGroup", function (collectionApi) {
return collectionApi.getFilteredByTags("post", "page");

You may also perform additional operations once you have this new collections array to further filter or sort the items.

Glob By File Type

You can create a new collection by selecting all templates by file type using getFilteredByGlob().

There are a few stipulations for these collections:

eleventyConfig.addCollection("onlyMarkdown", function (collectionApi) {
return collectionApi.getFilteredByGlob("**/*.md");

Collections From Template Front Matter Data

To create a collection based on front matter data, you can use a filter against all template content with getAll(). Then, you can access any front matter using and return the filtered collection by just checking if that key exists. Or, you could extend this to check for a particular value.

This technique is useful for grouping similar content beyond tags.

eleventyConfig.addCollection("specialCollection", function (collection) {
return collection.getAll().filter((item) =>;

Collections From Local Data

For accessing local data - as in, data returned from files within your _data directory - use the format getAll()[0].data.[customKey].

// Create collection from _data/customData.js

eleventyConfig.addCollection("customDataCollection", (collection) => {
const allItems = collection.getAll()[0].data.customData;

// Filter or use another method to select the items you want
// for the collection
return allItems.filter((item) => {
// ...

This is useful if you're not using pagination to generate template content. If you are using pagination, you can instead opt to assign paginated content to a collection via tags within the pagination process.

The all Collection

The special all collection is available by default for all template content, with no extra definition required. It is intended to allow you to access all of your site content, which is useful for things like sitemaps or RSS feeds.

To access all your template data, iterate over collections.all.

Filtered vs. Unique Collections

Instead of creating unique collections, existing collections can be passed into filters. Here are some considerations to help you choose which method to use.

Use filters:

Use collections:

Exclude Content From Collections

Sometimes you will want to remove a template from being included in collections. This attribute removes the template content from the all collection and any other defined collection.

eleventyExcludeFromCollections: true

Summary of Collection Creation Methods