Shopify line item properties in Liquid — a no-app tutorial

How do I add line item properties in Liquid without an app?

Add an input to product-form.liquid (or your theme's equivalent) with the name properties[Field Name]. The customer's input becomes a line-item property when they add to cart. Cart and email templates that include the standard properties loop will display it. Total code: 3-5 lines. Total setup: 5 minutes. Cost: free. Downsides: no live preview, no image validation, no per-field pricing add-on, no mobile UI polish — for those, use Print It My Way.

Step-by-step setup

1. Add input to product-form.liquid. Use name='properties[Field Name]' syntax.
2. Add validation attributes. maxlength, required, pattern — HTML5 attributes work.
3. Verify cart-item.liquid renders properties. Check the {% for property in item.properties %} loop.
4. Test add-to-cart, cart page, checkout, order confirmation. Property should appear on all four.

Step 1 — Add the input

Open sections/main-product.liquid or snippets/product-form.liquid. Inside the form, before the add-to-cart button, add:

<div class="product-form__personalization">
  <label for="engraving">Engraving text (max 20 chars)</label>
  <input
    id="engraving"
    type="text"
    name="properties[Engraving text]"
    maxlength="20"
    placeholder="Enter name"
  />
</div>

Multiple fields

Add as many properties[...] inputs as you need:

<input name="properties[Engraving text]" type="text" maxlength="20">
<input name="properties[Font]" type="hidden" value="Playfair Display">
<label>
  <input name="properties[Gift wrap]" type="checkbox" value="Yes">
  Add gift wrap (+$5)
</label>

Step 2 — Cart display

Verify sections/main-cart-items.liquid and cart-drawer.liquid include the properties loop:

{% for property in item.properties %}
  {% assign first_char = property.first | slice: 0, 1 %}
  {% if property.last != blank and first_char != '_' %}
    <dt>{{ property.first }}:</dt>
    <dd>{{ property.last }}</dd>
  {% endif %}
{% endfor %}

Step 3 — Validation

HTML5 attributes handle basic validation: required, maxlength, minlength, pattern. For richer validation (profanity blocklist, regex, image DPI), you'd need JavaScript — at that point an app makes more sense.

Step 4 — Pricing (limitations)

Native Liquid can't add a fee to a cart line. If "gift wrap" costs $5, either: (a) create a separate $5 fee product and add it to cart with a Liquid form action="/cart/add", or (b) use a product options app with Cart Transform for a clean single-line fee. Option (a) creates cart clutter; (b) is why apps exist.

When to graduate to an app

Move to Print It My Way (Free plan) when you need: live preview, image upload, per-character pricing, conditional logic, mobile-optimized field styling, or 3+ fields per product. The Liquid approach is fine for one text field on one product.

Frequently asked questions