Migrating from Eleventy

If your Eleventy site is Nunjucks, the templates mostly move as they are — same syntax, same {% include %}, same filters where they overlap. What does not move is eleventy.config.js, because Poops has no JavaScript config to move it into. That is the trade in one sentence: you lose the programmable build, you stop maintaining a bundler beside it.

Read the four hard stops first.

The thing	What happens	What you do
`permalink`	Not supported, templated or otherwise. Output path mirrors source path	Put the files where the URLs go. `about/index.njk` → `dist/about/index.html` still works, because it is a real directory
`addFilter` / `addShortcode`	No API to register them	Use the bundled filters and tags, or move the logic into the template. A whole template language can be a custom engine; a single filter cannot
`addCollection`	Collections are directories, not queries	A collection is a direct subdirectory of `markup.in`. Cross-cutting queries — "everything tagged X across the site" — become taxonomies within one collection, or they go
`eleventyComputed`	No computed data layer	Compute in the template, or put the value in front matter

Config, key by key

Everything in eleventy.config.js that has an equivalent:

Eleventy	Poops
`dir.input`	`markup.in`
`dir.output`	`markup.out`
`dir.includes`, `dir.layouts`	`markup.options.includePaths` — an array, so `_layouts` and `_partials` can both be on it
`dir.data` + `_data/*.js`	`markup.options.data` — an explicit list of JSON/YAML files. JavaScript data files have no equivalent
`addPassthroughCopy("img")`	`"copy": [{ "in": "src/img", "out": "dist/img" }]`
`addGlobalData("site", …)`	`markup.options.site`
`setTemplateFormats`	fixed: `.html`, `.md`, and `.njk` or `.liquid`
`addPlugin(pluginRss)`	`markup.options.feed`
`addPlugin(EleventyHtmlBasePlugin)`	`{{ relativePathPrefix }}` in templates, plus `baseURL` or `--base-url` when you deploy under a subpath
`eleventy-plugin-vite`, or your own bundler	`styles`, `scripts`, `postcss` — top-level keys in the same file
`addFilter`, `addShortcode`, `addTransform`, `addCollection`	no equivalent

The whole thing, for a blog that was Eleventy plus Vite:

{
  "markup": {
    "in": "src",
    "out": "dist",
    "options": {
      "engine": "nunjucks",
      "site": { "title": "My Site", "url": "https://example.com" },
      "includePaths": ["_layouts", "_partials"],
      "data": ["_data/site.json"],
      "sitemap": "sitemap.xml",
      "searchIndex": "search-index.json",
      "feed": { "collection": "blog", "out": "feed.rss" }
    }
  },
  "styles": [{ "in": "src/scss/index.scss", "out": "dist/css/styles.css", "options": { "minify": true } }],
  "scripts": [{ "in": "src/js/main.ts", "out": "dist/js/main.js", "options": { "minify": true, "format": "iife" } }],
  "copy": [{ "in": "src/img", "out": "dist/img" }],
  "watch": ["src"],
  "livereload": true
}

Collections: queries become directories

This is the conceptual change, and it is worth understanding before you move files.

In Eleventy, tags: post in front matter puts a page into collections.post no matter where the file lives. In Poops, the directory is the collection — every page under src/blog/ is in the blog collection, and the index file declares it:

---
title: Blog
collection: true
paginate: 10
sort: date
taxonomies: [tags]
---

Eleventy	Poops
`tags: post` in each file	put the file in `blog/`; the collection is automatic
`collections.post` in templates	`blog.items` — a global named after the directory
`collections.post` filtered by a second tag	`tags: [release]` in front matter + `taxonomies: [tags]` on the collection, which also builds `blog/tags/release/` as a real page
`addCollection` with a custom sort	`sort: date` or `sort: { by: "title", order: "asc" }`
`pagination: { data, size, alias }` in front matter	`paginate: 10` on the collection; the index template reads `blog.pageItems`, `blog.pageNumber`, `blog.totalPages`
`permalink: "page-{{ pagination.pageNumber }}/"`	fixed shape: page 1 at `blog/`, page N at `blog/N/`
`{% for post in collections.post %}`	`{% for post in blog.items %}`

A page whose front matter has eleventyExcludeFromCollections: true becomes published: false — which also stops the page being built at all, so if you need the page but not the listing, move it out of the collection directory instead.

Templates

Eleventy (Nunjucks)	Poops
`layout: base.njk`	`layout: base`, and the file is `_layouts/base.html` — the Nunjucks engine appends `.html` to the name, so layouts get renamed off `.njk` (Liquid appends `.liquid`). `theme/layout` resolves from `node_modules`
`{{ content \| safe }}` in the layout	`{% block content %}{% endblock %}` — the body is rendered into the block
`{% include "header.njk" %}`	same
`{{ page.url }}`	same, and `page.filePath`, `page.excerpt`, `page.wordcount` come free
`{{ post.data.title }}`	`{{ post.title }}` — items are flat, no `data` wrapper
`{{ "now" \| date: … }}` via a plugin	`{{ post.date \| date("MMM D, YYYY") }}` — dayjs tokens, with a `dateFormat` default
A shortcode you wrote for images	the `{% image %}` tag, with `poops-images` doing the resizing
A shortcode for code samples	`{% highlight 'javascript' %}`, or a Markdown fence — both highlighted at build time
`eleventy-plugin-syntaxhighlight`	nothing to install; it is on by default

The order that works

Point markup.in at your existing dir.input. Underscore directories are ignored for output already, so _layouts and _includes keep working once they are on includePaths. Rename layout files from .njk to .html and drop the extension from the layout: line.
Move tagged posts into a directory named for the collection, and put collection: true in its index file.
Delete every permalink and move the file to match the URL it declared.
Replace collections.x with x.items and drop .data from item property access.
Port shortcodes and filters to bundled tags, or inline them. This is the step that decides whether the migration is an hour or a weekend — count them before you start.
Move the bundler config into scripts/styles and delete the Vite config, the npm-run-all script and the second watcher.
poops -b, then read the warnings. Missing date: front matter is the common one.

Note

This is a mapping, not a script. Nothing here was run against an existing Eleventy site — the Poops side of every row is documented behaviour, the Eleventy side is from its docs, and your site will have a case neither of us thought of.

When not to migrate

You wrote a dozen shortcodes, your data comes from an API at build time, or your URLs are generated from a permalink template. Eleventy's programmable config is doing real work there, and Poops has nowhere to put it — the comparison has the rest of the rows.