Comparer for Craft CMS

Side-by-side comparison for Craft CMS 5. Visitors build a list of products — or entries, or categories — and see them in a comparison table you define once in the control panel.

WooCommerce shops have had this for years, via plugins like WPC Smart Compare. Craft has not, and the reason those plugins do not translate is that they compare products: their table is a fixed list of known product properties. Craft's content is whatever you modelled it to be.

Comparer's answer is that a table row is a resolver, not a column. A row knows how to read itself off whatever element it is handed. So one mechanism draws a laptop's processor and ramGb, a sofa's price and stock, and a case study's industry and duration — and the difference highlighting works the same way for all of them.

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What it does

• Compare anything. Commerce products and variants, entries, categories. One element type per comparison set; as many sets as you need.
• A table you define in the CP. Drag rows into order: the title, an image, any custom field, element attributes, price, SKU, stock, an add-to-cart button, a link — or a Twig template when none of those fit.
• Difference highlighting that means something. Rows whose values agree are greyed out and can be hidden entirely. Comparison happens on normalized values, not rendered markup, so $10.00 and $10 are the same price and two relation fields holding the same three entries in a different order are the same answer.
• Lists that survive. A guest's comparison lives in the database under a cookie token, not in the cookie. Sign in and it merges into your account. Come back on your laptop and it is there.
• A comparison bar and a modal, both zero-dependency, both progressively enhanced from real forms that work with JavaScript switched off.
• A real page at /compare that can be bookmarked, printed and — on Pro — shared by link.
• Insights (Pro): which products your customers put next to each other. That is your competitive set as they see it, which is rarely how your catalogue is organised.

Commerce is a soft dependency. Comparer works perfectly well on a content site with no shop.

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Requirements

Craft CMS	5.3+
PHP	8.2+
Craft Commerce	5.0+, optional — needed only for product, price, SKU, stock and cart rows

Installation

composer require justinholtweb/craft-comparer
php craft plugin/install compare

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Getting started

1. Create a comparison set

Settings → Comparer → Sets → New comparison set.

• Name and handle — the handle is what templates and endpoints use.
• What does this set compare? — Entries, Categories, or (with Commerce) Products or Variants.
• Which ones? — tick the sections, category groups or product types in the set. Tick nothing to include all of them.
• Maximum items — how many go side by side. Three fits a phone; ten is the Pro ceiling.
• Table rows — the point of the screen. Add rows, choose a type, set a label, drag to reorder.

2. Put a compare button on your product cards

{{ craft.comparer.button(product) }}

That is the whole integration. It renders a real form posting to Comparer's toggle action, and the bundled runtime turns it into a fetch. Add the bar once in your layout:

{{ craft.comparer.bar() }}

3. That is it

Visitors add things, the bar appears, "Compare (3)" opens the table. /compare shows the same table as a page.

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Templating

Every method takes an optional set handle. With one set — every Lite install and most Pro ones — you can leave it out.

{# state #}
{{ craft.comparer.count() }}                  {# how many are on the list #}
{{ craft.comparer.has(product) }}             {# is this one on it? #}
{{ craft.comparer.isFull() }}
{{ craft.comparer.items() }}                  {# the elements, in list order #}
{{ craft.comparer.list() }}                   {# the CompareList model #}
{{ craft.comparer.url() }}                    {# the comparison page #}
{{ craft.comparer.setFor(product) }}          {# which set this element belongs to #}
{{ craft.comparer.sets }}

{# ready-made markup #}
{{ craft.comparer.button(product) }}
{{ craft.comparer.button(product, { text: 'Add to compare', addedText: 'Added', class: 'btn' }) }}
{{ craft.comparer.bar() }}

{# the table #}
{{ craft.comparer.render() }}                                  {# the visitor's own list #}
{{ craft.comparer.render(products) }}                          {# these elements, right now #}
{{ craft.comparer.render(null, { differencesOnly: true }) }}

{# or build it and draw it yourself #}
{% set table = craft.comparer.table() %}
{% for row in table.getVisibleRows(true) %}
    <tr class="{{ row.isUniform() ? 'same' : 'differs' }}">
        <th>{{ row.getLabel() }}</th>
        {% for cell in row.cells %}
            <td>{{ cell.isEmpty() ? '—' : cell.html }}</td>
        {% endfor %}
    </tr>
{% endfor %}

Rolling your own buttons

Any element with the right data attributes is picked up, including ones added to the page later by your own JavaScript:

<button data-comparer-toggle="{{ product.id }}" data-comparer-set="products">Compare</button>
<span data-comparer-count="products">0</span>
<a href="{{ craft.comparer.url() }}" data-comparer-open="products">Compare now</a>
<button data-comparer-clear="products">Clear</button>
<button data-comparer-remove="{{ product.id }}" data-comparer-set="products">Remove</button>

The runtime fires comparer:changed and comparer:toggled on document, and exposes window.craftComparer.refresh(), .open(setHandle) and .state().

Overriding the markup

To replace	Create
The comparison table	templates/comparer/_table.twig
The comparison page	templates/comparer/index.twig
One set's table only	set a Custom table template on the set

Table templates get table, set, differencesOnly, settings and plugin.

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Row types

Row	What it reads	Needs
Title	The element's title, optionally linked
Image	An asset field, or the first one it finds
Custom field	Any field, rendered and normalized by type
Element attribute	Post date, expiry, created, updated, slug, ID, status, author
Link	A "View" button
Price	Cheapest variant, default variant, or a range	Commerce
SKU	The purchasable's SKU	Commerce
Stock	In stock / out of stock, or the count	Commerce
Add to cart	A real Commerce add-to-cart form	Commerce
Twig template	Whatever you render	Pro

A field handle that is not on a particular element gives that cell a blank rather than an error — which is the normal case for a set spanning two entry types, not a mistake.

Plugins can register their own:

Event::on(Rows::class, Rows::EVENT_REGISTER_ROW_TYPES, function(RegisterComponentTypesEvent $e) {
    $e->types[] = MyRatingRow::class;
});

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The JSON API

Every endpoint the bundled runtime uses is public and documented, so you can turn off Load the bundled front end and drive it from your own build.

Method	Endpoint	Body
GET	/comparer/session.json	—
POST	compare/list/add	elementId
POST	compare/list/remove	elementId
POST	compare/list/toggle	elementId
POST	compare/list/clear	set
POST	compare/list/reorder	set, ids[]
GET	compare/list/table	set, optional ids, differencesOnly, format=json
POST	compare/list/share	set (Pro)

session.json is the one to start with. It returns a fresh CSRF token and the current state of every set:

{
  "csrfTokenName": "CRAFT_CSRF_TOKEN",
  "csrfToken": "…",
  "loggedIn": false,
  "mayCompare": true,
  "sets": {
    "products": { "count": 2, "max": 4, "full": false, "items": [ … ] }
  }
}

Why that endpoint exists

Comparer’s buttons live on product cards, and product cards live on cached pages — {% cache %}, Blitz, a CDN. On a cached page the CSRF token is stale and the button does not know whether the visitor already added this product. So the runtime never trusts the HTML it was rendered into: it fetches the session, takes the token from there, and reconciles the buttons. Cached and uncached pages then behave identically.

A refusal — a full list, or "please sign in" — comes back as 200 with success: false and a human-readable error. It is an answer, not a fault.

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Settings

Setting	Default
Comparison page URI	compare	Must not clash with an entry URI
Comparison bar position	Bottom	Or top, or none
Open when full	Off	A modal nobody asked for is an interruption
Load the bundled front end	On	Off if you are driving the API yourself
Require login	Off
Guest list lifetime	30 days	Signed-in users' lists never expire
Cookie name	CraftComparerToken	Holds a token, never the list
Record insights	On	Pro. Element IDs only — no personal data
Keep insights for	90 days	Swept by Craft's garbage collection
Share link lifetime	Forever	Pro

Console

php craft comparer/maintenance         # what Comparer currently holds
php craft comparer/maintenance/prune   # drop abandoned guest lists and expired events

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Editions

	Lite	Pro
Price	Free	$79, then $29/year
Comparison sets	1	Unlimited
Items per comparison	3	Up to 10
All core row types	✓	✓
Guest + user lists, merged on login	✓	✓
Bar, modal, standalone page, print	✓	✓
Twig API + JSON endpoints	✓	✓
Custom table templates	✓	✓
Difference highlighting and "differences only"	—	✓
Twig template rows	—	✓
Shareable comparison links	—	✓
Insights	—	✓

Lite is a complete comparator, not a demo. A shop with one catalogue and a three-up table — which is what almost every comparison table on the web actually is — never meets a paywall.

A lapsed Pro licence narrows rather than breaks: the table drops to three columns and the Twig rows are skipped, but the page keeps working and nothing stored is changed. Renewing brings it all back.

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Privacy

Comparer stores element IDs, a random guest token, and — for signed-in visitors — a user ID. It records no IP addresses, no user agents, and makes no outbound requests of any kind. Insights are element IDs and timestamps.

Guest lists are deleted after their configured lifetime. Signed-in users' lists are their data and are deleted with their account.

Licence

Proprietary. See LICENSE.md.