Short answer — yes. There are three practical ways to automatically add free gifts to a Shopify cart:

• Install a “auto add gift” app (fast, works on any Shopify plan).
• Build a theme-side solution that uses the Ajax Cart API to add/remove a gift variant (works on all plans) — but you must also handle making it free server-side or accept security tradeoffs.
• If you’re on Shopify Plus, use theme JS to add the gift + a Shopify Script (Script Editor) to set the gift line item price to $0 (safer because the discount is enforced server-side).

Below I explain each approach, when to use it, and give copy‑paste-ready code/examples.

1. Use an app (recommended if you want speed & reliability)

• Apps handle the edge cases (remove gift if customer removes the qualifying product, apply promo only when stock exists, support gift pickers, etc.). Examples: CartBot / EG Auto Add / Fokkio / AutoCart and many others on the Shopify App Store. These apps are the easiest, require no custom development, and work across themes and checkout. (apps.shopify.com)

When to pick this: you want fast setup, non‑technical control panels, scheduling, customer targeting.

2. Theme + Ajax API (custom code; works on all plans) How it works in short:

• Add JavaScript to your theme to monitor the cart (or run on cart page / cart updates).
• When conditions are met (cart subtotal, contains certain product, etc.) POST the gift variant to /cart/add.js. Remove the gift if the condition no longer holds. The Ajax API is the official way to add items from theme JS. (shopify.dev)

Basic example (vanilla JS) — put in theme JS (e.g., assets/theme.js) and adapt variantId, threshold, selectors:

// config const GIFT_VARIANT_ID = 1234567890; // replace with your variant id const MIN_SUBTOTAL = 5000; // cents = $50.00

async function getCart() { const res = await fetch('/cart.js'); return res.json(); }

async function addGift() { await fetch('/cart/add.js', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ items: [{ id: GIFT_VARIANT_ID, quantity: 1 }] }) }); }

async function removeGift() { // find cart, set gift qty to 0 if present const cart = await getCart(); const giftItem = cart.items.find(i => i.variant_id === GIFT_VARIANT_ID); if (giftItem) { await fetch('/cart/change.js', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ id: giftItem.key, quantity: 0 }) }); } }

async function checkGiftRule() { const cart = await getCart(); const subtotal = cart.items_subtotal_price; // cents const hasOtherItems = cart.item_count - (cart.items.find(i => i.variant_id === GIFT_VARIANT_ID)?.quantity || 0) > 0; if (subtotal >= MIN_SUBTOTAL && hasOtherItems) { // add if not already there if (!cart.items.some(i => i.variant_id === GIFT_VARIANT_ID)) await addGift(); } else { await removeGift(); } }

// run on page load and after cart updates checkGiftRule(); // hook this to your cart update events / Ajax cart callbacks

Notes and cautions:

• You must obtain the variant ID for the gift (visit /products/your-product.js or view product JSON to find variant IDs). (barn2.com)
• This approach adds the product to cart on the client, but it does NOT, by itself, make that line item free in a way a customer can’t abuse. If you don’t enforce the 100% discount server-side, a savvy user could remove the line item property or add the variant via console and get it free. See the security note below. (community.shopify.com)

When to pick this: you are on a non‑Plus plan, comfortable with JS, and accept either (A) using an app/discount for pricing or (B) some risk / manual checks.

3. Shopify Plus — Theme JS + Script Editor (safer) How it works:

• Theme JS automatically adds the gift variant into the cart (same Ajax flow above).
• A Shopify Line Item Script (Script Editor) runs server side during cart/checkout and sets the gift line price to zero when rules are met (you can check product tags, line item properties, cart subtotal, etc.). That makes the free gift enforcement server-side, preventing client-side tampering. Script Editor is available only on Shopify Plus. (help.shopify.com)

Example of the Script Editor logic (Ruby, simplified):

• tag your gift product with a tag like "free-gift" and add a line item property or detect a condition.

inside a Line Item script

gift_tag = 'free-gift' message = 'FREE GIFT'

Input.cart.line_items.each do |li| if li.variant.product.tags.include?(gift_tag) # only zero price if cart meets your condition, e.g. items_subtotal_price if Input.cart.subtotal_price >= Money.new(cents: 5000) && Input.cart.line_items.size > 1 li.change_line_price(Money.zero, message: message) end end end Output.cart = Input.cart

Notes:

• Shopify Scripts can discount line items and change checkout options but cannot create new line items for the cart by themselves; that’s why the theme JS add + Script zeroing pattern is common. The community and docs discuss this exact approach and the security tradeoffs when trying to do everything in client-side code. (community.shopify.com, help.inveterate.com)

Important operational notes and best practices

• Security / abuse: client-only solutions that add a “gift” and then rely on JS to zero its price are abusable. For a robust, un‑cheatable solution you need server-side enforcement (Shopify Script on Plus or an app that enforces discounts). (community.shopify.com)
• Variant IDs: get them via /products/{handle}.js or view variant JSON in the product admin / storefront. (barn2.com)
• Ajax API endpoints: use /cart.js, /cart/add.js, /cart/change.js for reads and writes from theme JS. (shopify.dev)
• Scripts deprecation: Shopify has been moving toward Shopify Functions; Scripts/Script Editor remain available for Shopify Plus but Shopify gives deprecation/migration guidance — verify current status for long‑term plans. (Check Shopify docs for the most current timeline before you commit.) (help.shopify.com)

Recommendation (quick)

• If you want a reliable, low‑work solution: install a well‑rated auto‑gift app from the Shopify App Store. (apps.shopify.com)
• If you’re on Plus and want full control and secure enforcement: implement theme JS to add the gift + a Line Item Script to zero its price. (help.shopify.com, help.inveterate.com)
• If you’re on a standard plan and want to build it yourself: use theme JS + either (A) an app to enforce the discount at checkout or (B) accept the risk / add manual order checks.

If you want, I can:

• give a ready‑to‑paste theme JS file customized to your variant ID and rule; or
• draft the exact Line Item Script (Ruby) for a Shopify Plus store (you’ll need to provide the gift product tag/variant ID and the trigger rule); or
• list the top 4 apps (with links and pro/con for each) and recommend which fits your use case.

Which of the three options above do you want to move forward with?