Shopify Functions vs Shopify Scripts: What's the Difference?

If you run a Shopify Plus store, you already know the power of checkout customization. For years, Shopify Scripts was the go-to tool for building custom discount logic, shipping rules, and payment flows. But that era is ending.

Shopify officially deprecated Scripts, and on June 30, 2026, they stopped working entirely. Starting April 15, 2026, you can no longer edit or publish new Scripts. If your store still runs custom checkout logic on Scripts, the clock is ticking.

The replacement is Shopify Functions and it is not just a like-for-like swap. Functions are a fundamentally different technology built on a different architecture, a different programming model, and a dramatically higher performance ceiling.

This guide breaks down exactly what changed, what each technology does, and what Shopify Plus merchants need to do right now.

What Are Shopify Scripts?

Shopify Scripts launched in 2016 as a Shopify Plus-exclusive feature. They were small Ruby-based programs that ran inside Shopify's Script Editor and let merchants apply custom logic to three core areas:

• Line item scripts: custom discounts on individual products, bundles, or collections
• Shipping scripts: hide, rename, reorder, or apply conditions to shipping methods
• Payment scripts: show or hide payment gateways based on cart conditions

Scripts were powerful for their time. They let Plus merchants go beyond Shopify's native discount and shipping tools, creating personalized checkout experiences without building a full custom app. However, they came with significant limitations that became harder to ignore as stores grew.

Scripts ran in a sandboxed Ruby environment on Shopify's servers. That sandbox had tight execution limits, was prone to timeouts during high-traffic periods like flash sales, and required developers to write and maintain Ruby code - a language that most modern Shopify developers don't specialize in. Every change required going back into the Script Editor and republishing, making iteration slow and risky.

Most importantly, Scripts were only available on Shopify Plus, locking out the majority of Shopify merchants from advanced checkout customization entirely.

What Are Shopify Functions?

Shopify Functions are Shopify's modern extensibility platform for backend checkout logic. Rather than sandboxed Ruby scripts, Functions are compiled WebAssembly modules that run directly inside Shopify's own infrastructure at key points in the commerce lifecycle.

You write Functions using JavaScript, TypeScript, Rust, or AssemblyScript. The Shopify CLI compiles your code to WebAssembly and deploys it as part of a Shopify app. This architecture means Functions execute at sub-5ms speeds, with no cold starts and consistent performance regardless of traffic volume.

Here is what sets Functions apart structurally:

• They are distributed as apps - merchants install a Functions-powered app from the Shopify App Store or a custom app, rather than writing code in a Script Editor
• Configuration happens in the Shopify admin UI - non-technical teams can adjust rules without touching code
• Functions work across all Shopify plans when accessed via an installed app, not just Shopify Plus
• A single discount Function can target order-level, product-level, and delivery-level discounts simultaneously - something Scripts could never do

Shopify Functions cover all the use cases Scripts handled and significantly more. The current Function APIs include Discount Functions, Payment Customization, Delivery Customization, Cart and Checkout Validation, Order Routing, and more, with the platform continuously expanding.

Shopify Functions vs Shopify Scripts: Side-by-Side Comparison

Key Differences Explained

1. Architecture and Performance

This is the most fundamental difference. Shopify Scripts ran in a separate sandboxed environment, which introduced latency and failure risk. During high-traffic events, Scripts were a known weak point slow to execute, prone to timeouts, and difficult to debug.

Shopify Functions run as compiled WebAssembly directly within Shopify's infrastructure. There is no separate environment to spin up, no Ruby interpreter overhead, and no cold start delay. The result is consistent, predictable execution regardless of whether your store is processing 10 orders or 10,000 per hour.

2. Who Can Use Them

Shopify Scripts were exclusively available to Shopify Plus merchants. This meant thousands of growing stores on Advanced or lower plans had no access to custom checkout logic at all.

Shopify Functions change this. While building custom Functions requires developer access and Shopify Partners, any merchant on any plan can install an app built on Functions. This opens the entire ecosystem of checkout customization upsells, custom discount rules, shipping logic, payment method control to all Shopify stores.

3. How Merchants Interact With Them

With Scripts, every change to discount logic or shipping rules meant going into the Script Editor and editing Ruby code. Non-technical merchants were completely dependent on developers for even minor adjustments like changing a minimum order threshold for a discount.

Functions flip this dynamic. Once a Function-powered app is installed, merchants configure everything through the Shopify admin interface. Want to change the free shipping threshold? Update it in the app settings. Want to hide a payment method for international customers? Set the condition in the UI. No developer involvement required for day-to-day rule management.

4. Scope and Flexibility

Shopify Scripts were siloed. A line item script only affected line items. A shipping script only touched shipping. There was no way to apply logic that spanned multiple aspects of the checkout in a single script.

Functions are built for composability. A single discount Function can target order-level discounts, product-level discounts, and delivery discounts simultaneously. Payment customization Functions can reference cart contents, customer tags, and order value in the same condition set. You can activate up to 25 payment customization Functions per store, enabling granular control over different customer segments at the same time.

5. The Deprecation Timeline

The deadline is not moving. Here are the critical dates every Shopify merchant needs to know:

• April 15, 2026 - You can no longer edit or publish new Scripts
• June 30, 2026 - All Shopify Scripts stop executing permanently

If your Scripts are still active on June 30, 2026, Shopify will not show an error. Your checkout will simply revert to default Shopify behavior - with no custom discounts, no custom payment logic, and no shipping customizations. For stores running complex promotional pricing or B2B wholesale rules, this could mean significant revenue disruption from day one.

What Happens to Your Store If You Do Not Migrate?

This is the most urgent practical question. If you take no action before June 30, 2026:

• All custom discount logic built in Scripts stops executing - automatic discounts, tiered pricing, BXGY offers all revert to default
• Custom payment method rules disappear - gateways you have hidden or reordered will all appear at checkout again
• Custom shipping logic stops - all shipping methods show by default, in Shopify's default order
• Any customer-facing experience built around your Script logic breaks silently

There is no grace period, no opt-out, and no extension. Shopify has confirmed this timeline definitively.

How to Migrate from Scripts to Functions

Migration is not a direct translation - it is a rebuild. Scripts and Functions use different data models, different programming languages, and different deployment mechanisms. Here is the recommended path:

Step 1: Audit Your Current Scripts

Use Shopify's Scripts Customizations Report in your admin panel. This generates a list of every active Script on your store, including its type, name, and source. Export it as a CSV for a full inventory.

Step 2: Categorize Each Script

Group your Scripts into three buckets:

• Scripts you no longer need - drop them
• Scripts replaceable by a public app - find a Functions-powered app on the Shopify App Store
• Scripts requiring custom logic - plan a custom Function build with a developer

Step 3: Choose Your Migration Path

For most merchants, a Functions-powered app like Checkout Boost handles the most common use cases: custom discount rules, BXGY offers, checkout upsells, free gifts, payment and shipping customization - without any custom development. For complex B2B or enterprise logic, you may need a custom app built by a Shopify Partner.

Step 4: Test Before Go-Live

Always test new Functions in a development or staging environment before publishing to your live store. Validate all discount conditions, shipping rules, and payment logic against different cart scenarios. Test during simulated peak load if possible.

Step 5: Run Scripts and Functions in Parallel

Shopify allows both to coexist until the June 30 deadline. Use this window to verify your new Function-based logic is working correctly before decommissioning old Scripts.

The No-Code Migration Path with Checkout Boost

For Shopify Plus merchants who do not want to manage custom app development, Checkout Boost provides a fully managed, no-code path from Scripts to Functions.

Checkout Boost is built natively on Shopify's Checkout Extensibility and Functions platform, which means everything it does upsells, free gifts, BXGY, custom discount rules, payment method customization, shipping rules, checkout forms, trust badges runs on Functions under the hood. You configure all of it through a drag-and-drop editor in the Shopify admin, with no code required.

If your current Scripts handle discount logic, promotional offers, or checkout customization, Checkout Boost can replicate and enhance that functionality without a single line of Ruby, and well ahead of the June 2026 deadline.

Frequently Asked Questions

Will my store break immediately if I don't migrate before June 30, 2026?

Not before the deadline. Scripts will continue running as normal until June 30, 2026. However, on that date they stop executing immediately and permanently. There is no gradual phase-out after the deadline; it is a hard cutoff.

Can Shopify Functions and Shopify Scripts run at the same time?

Yes. Shopify supports running both simultaneously, which gives you a safe migration window to test and validate your new Function-based logic before turning off Scripts.

Do I need a developer to use Shopify Functions?

It depends. Building a custom Function from scratch requires developer skills in JavaScript, TypeScript, or Rust. However, installing and configuring a Functions-powered app like Checkout Boost requires no coding at all. Most common Script use cases can be replaced with a no-code app.

Are Shopify Functions only available on Shopify Plus?

No. Any Shopify merchant can install and use apps built on Shopify Functions. Building your own custom Functions as a developer does require access through Shopify Partners, but the functionality is available to all plan levels via installed apps.

What Script types does migration affect?

Migration affects all three Script types: line item scripts (discounts), shipping scripts, and payment scripts. Each has corresponding Function APIs - Discount Functions, Delivery Customization Functions, and Payment Customization Functions respectively.

Is the June 30, 2026 deadline confirmed or could it be extended again?

Shopify has explicitly confirmed June 30, 2026 as the final deadline with no further extensions. The platform investment has fully shifted to Functions, and the Scripts infrastructure is being decommissioned. The April 15, 2026 editing freeze is already in effect.

What if my Script logic cannot be replicated with existing Functions APIs?

Shopify's Functions API surface is expanding continuously. If a specific capability is not yet available, Shopify recommends continuing to use Scripts for that case only until the API supports it - but this does not change the June 30 hard deadline. Any Script that cannot be migrated before then will simply stop working.

How long does migration typically take?

For simple to moderate Script logic replaceable by a public app, migration can be completed in hours. For complex custom Scripts requiring bespoke Function development, plan for several weeks including development, testing, and validation. Starting now is critical developer availability will become limited as the June deadline approaches.

The Bottom Line

Shopify Scripts and Shopify Functions serve the same surface purpose - custom checkout logic - but they are built on fundamentally different foundations. Functions are faster, more flexible, more accessible, and more future-proof in every measurable way.

The migration is not optional. June 30, 2026 is a hard deadline, and the cost of inaction is a broken checkout on the day your Scripts stop executing.

The good news is that for most merchants, migration does not require rebuilding from scratch. Functions-powered apps like Checkout Boost replace everything Scripts handled, and add upsells, BXGY, AI product recommendations, custom forms, and branding tools that Scripts could never touch all through a no-code interface designed for Shopify Plus merchants who want more revenue from every checkout.

Start your migration today. The merchants who move now will have a stable, tested, higher-performing checkout well before the June deadline and a significant head start on the competition.