If your Shopify Plus store runs any custom discount logic, tiered pricing, bundle rules, or cart-level promotions through Shopify Scripts, you have a hard deadline to act on: June 30, 2026. After that date, Scripts will no longer be supported, meaning any active logic residing within your legacy Script Editor will essentially cease to function, potentially leaving your checkout flows broken and your pricing strategies misaligned.

This guide covers exactly what that means, what Shopify Functions are, what breaks if you miss the deadline, and how to run a clean migration — whether you handle it internally or bring in outside help. We have structured this content to provide a granular roadmap for technical stakeholders and operations leads alike, ensuring that your transition to the modern Shopify architecture is completed with total precision.

No filler. Just what you need to make a confident, informed decision while mitigating the operational risks associated with this fundamental platform transition.

What Is Shopify Scripts and Why Is It Being Deprecated?

Shopify Scripts was a Ruby-based customization layer available exclusively to Shopify Plus merchants that allowed brands to inject custom business logic directly into the checkout pipeline. It allowed merchants to write custom logic that ran at checkout — controlling how discounts were applied, how line items were modified, and how shipping rates were calculated, providing a level of control that was historically unavailable on the standard platform.

For years, it was the only way to build sophisticated promotional logic directly inside the checkout, acting as the primary engine for complex revenue-driving operations. If you had a "buy 3, get 1 free" rule, a tiered wholesale discount structure, or a loyalty-based pricing tier, there's a high probability Scripts was doing that work, serving as a critical piece of your infrastructure.

The problem is that Scripts ran on Shopify's servers, in a sandboxed Ruby environment, with significant limitations — slow execution, difficult testing, no version control, and limited visibility for non-developers, which created a "black box" scenario that was difficult to maintain over time.

As Shopify's checkout infrastructure matured (particularly with the launch of Checkout Extensibility), Scripts became a technical liability rather than an asset, as the platform moved toward a more performant, modular, and developer-friendly architecture. Shopify's solution is Shopify Functions — a fundamentally different architecture that addresses most of what made Scripts painful to work with, offering better stability, modern coding standards, and significantly faster execution speeds during the crucial checkout phase.

What Are Shopify Functions?

Shopify Functions are server-side WebAssembly (Wasm) modules that run inside Shopify's infrastructure, representing a massive technological leap forward for enterprise-grade customization. They replace Scripts across the same core use cases but with a modern, extensible architecture built for scale, performance, and long-term maintainability within the Shopify ecosystem. Where Scripts were closed, opaque, and hard to test, Functions are:

• Language Flexible — Written in modern languages like Rust, JavaScript, or TypeScript (via the official Functions SDK) for broader developer accessibility.

• Version Controlled — Managed through standard software development lifecycles like any other code in your private or public application repository.

• Locally Testable — Capable of being validated in a local development environment before deployment, preventing production-level errors during the rollout.

• App-Integrated — Deployed as an integrated part of a Shopify app, allowing for cleaner code management and better decoupling of logic from the storefront admin.

• API Stable — Governed by Shopify's robust Function APIs, which are designed to be stable, documented, and fully supported for high-traffic enterprise environments.

  Functions currently cover five primary APIs that map directly to what Scripts handled:

• Cart and Checkout Validation — block checkout based on cart rules, ensuring customers meet minimums or follow specific purchase requirements.

• Discounts — order discounts, product discounts, and shipping discounts that utilize the native discount engine for seamless application.

• Payment Customization — show, hide, or reorder payment methods dynamically based on customer attributes or regional cart criteria.

• Delivery Customization — control shipping option display, allowing for dynamic carrier filtering based on package contents or destination.

• Cart Transform — modify line items, bundles, or pricing presentation, enabling sophisticated kitting and custom pricing workflows that were previously difficult to manage.

  If your Scripts logic lives in one of those areas, a Function equivalent exists, though the architectural shift requires a re-evaluation of how your business rules are structured and delivered within the new environment.

What Breaks on June 30, 2026?

After the deprecation date, any Scripts currently running in your Shopify Plus store will stop executing entirely, meaning your checkout will revert to native Shopify behaviors without your custom overrides. Shopify has been clear: there is no grace period extension, and the platform will force the transition to ensure all merchants are operating on the modern, secure Checkout Extensibility framework. What that means in practice:

• Discount Failures — Discount logic controlled by Scripts will silently stop applying, leading to potential customer support issues and lost revenue.

• Pricing Reversions — Tiered pricing rules will revert to standard catalog pricing, which may severely impact wholesale or B2B customer retention.

• Bundle Disappearance — Bundle discounts will disappear at checkout if they relied on Script-based line-item modifications.

• B2B Logic Failures — Wholesale or B2B pricing tiers controlled by Scripts will fail to apply, potentially alienating your most valuable recurring account customers.

• Promotion Inactivity — Any cart-level promotional rules written in Scripts will not fire, rendering your marketing campaigns ineffective at the moment of conversion.

  For most stores, this is not a minor inconvenience; this is revenue-impacting at scale, potentially causing a major dip in average order value and overall conversion rates during the transition window. A customer expecting a 20% tiered discount getting charged full price is a conversion killer and a trust issue that can permanently damage your brand's reputation with loyal shoppers. The risk is not hypothetical, as the deadline is fixed and the impact scales directly with how much promotional and pricing logic you have running through Scripts today.

The Scripts-to-Functions Migration Readiness Matrix

Use this framework before you scope any migration work, as it helps you categorize your existing Scripts by complexity and prioritize your developer resources accordingly to ensure a smooth transition.

Migration Readiness Matrix

Each Script in your store falls into one of four quadrants based on two dimensions: logic complexity (low to high) and business criticality (low to high).

• Quadrant 1 — Migrate Now (High Criticality, Low Complexity) — Simple discount rules that directly affect checkout pricing, such as percentage-off promotions or fixed-amount discounts based on product tags. These are your first priority; Functions handle them cleanly, and migration risk is low, making them ideal for initial testing.

• Quadrant 2 — Plan Carefully (High Criticality, High Complexity) — Multi-condition logic tied to revenue-critical flows, such as tiered wholesale pricing, loyalty-based discount stacking, or bundle pricing with conditional exclusions. These require proper discovery, detailed technical documentation, testing, and staging before you touch the production environment.

• Quadrant 3 — Fast-Follow (Low Criticality, Low Complexity) — Promotional rules that are live but not core to your margin or conversion, such as a one-off campaign discount or a basic free-shipping threshold rule. Migrate these after your Quadrant 2 work is stable, ensuring your core business remains protected throughout the process.

• Quadrant 4 — Audit and Decide (Low Criticality, High Complexity) — Complex logic that isn't driving significant business impact. Before migrating, ask whether this logic is still needed at all, as deprecation is a golden opportunity to clean house and remove technical debt.

  Run every active Script through this matrix before writing a single line of Functions code to ensure your team focuses on the highest-value migrations first.

How to Audit Your Existing Scripts

Before migration work begins, you need a complete inventory of every piece of logic currently controlling your checkout to avoid surprises on the June 30 deadline. Here is how to do it:

• Step 1: Access the Script Editor — In your Shopify Plus admin, navigate to Apps > Script Editor. Every active and draft Script is listed here; do not assume your developers or previous agency handed everything off cleanly, as undocumented scripts are a major risk.

• Step 2: Document Each Script — For every Script, record: the name, the type (line item, shipping, payment), whether it is active or draft, a plain-language description of what it does, and who owns it internally.

• Step 3: Map Scripts to Business Rules — For each Script, identify the corresponding business rule or promotional mechanic it supports. This is often where teams discover Scripts running logic that no one currently on the team fully understands, which necessitates an immediate interview with stakeholders to confirm if the logic remains relevant.

• Step 4: Identify Dependencies — Some Scripts interact with other tools — loyalty apps, subscription platforms, or ERP pricing feeds. Flag those dependencies before scoping Functions replacements to prevent breaking secondary integrations.

• Step 5: Prioritize Using the Matrix — Apply the Readiness Matrix from the previous section to create a prioritized migration backlog, turning a potentially chaotic project into an orderly, task-oriented development sprint.

How Shopify Functions Migration Actually Works

Once your audit is complete, the migration process follows a consistent pattern regardless of the specific Script type, emphasizing a modern development workflow.

Functions live inside apps. Unlike Scripts, which lived directly in your admin, Functions are deployed as part of a Shopify app, providing a more robust container for your custom code. If you have a development team, they will build a custom app (private or internal) that contains your Function logic. If you use an agency or external developer, they will deliver the same, ensuring that your logic is modular, maintainable, and version-controlled.

The development workflow looks like this:

• Install CLI — Install the Shopify CLI and set up a Functions-compatible app structure.

• Target API — Choose your target Function API (e.g., the Discounts API for discount logic) to ensure compatibility.

• Logic Writing — Write the Function logic in JavaScript/TypeScript or Rust for performance and reliability.

• Local Testing — Test locally using the Shopify Functions testing tools to catch logic errors before any deployment.

• Staging QA — Deploy to a staging store and QA against your original Script behavior to verify functional parity.

• Production Deployment — Deploy to production and monitor closely for any unexpected checkout behaviors.

  What to test before going live:

• Every discount scenario your Scripts handled, run end-to-end to ensure math accuracy.

• Edge cases: zero-quantity items, mixed product types, and complex discount code stacking.

• Performance under load if your store sees high traffic volume during peak promotional periods.

• Behavior when the Function encounters unexpected input, ensuring the checkout remains stable.

  Do not migrate directly to production; the checkout is not a place to discover bugs, and a staging environment is mandatory for professional Shopify operations.

Common Mistakes and Trade-Offs

• Mistake 1: Waiting Until Q2 2026 — The deadline is June 30. If you start planning in April, you are running a sprint under pressure with no buffer for QA, which increases the likelihood of shipping broken checkout logic.

• Mistake 2: Assuming It Is a Direct Swap — Functions are not a line-for-line translation of Script syntax; the logic needs to be rebuilt in a new language, against a different API, meaning experienced Script logic does not simply copy-paste into Functions.

• Mistake 3: Ignoring App Ownership — Functions require a Shopify app container. Who owns that app, who maintains it, and how does it get updated going forward? Answer this before deployment, as you do not want to be reliant on a developer who is no longer available.

• Mistake 4: Skipping QA on Discount Stacking — If your store allows multiple discounts to stack, or if you use automatic discounts alongside code-based discounts, test every combination, as this is where migration issues typically surface.

• Mistake 5: Not Cleaning Up Deprecated Scripts — Once a Function is live and validated, remove the corresponding Script. Running both creates confusion and potential conflicts; keep your environment clean and your logic transparent.

  Trade-off to understand: Functions require app infrastructure. Scripts were simple to spin up because they lived natively in the admin, but Functions require app deployment and ongoing maintenance. This is the right trade for scalability and reliability, but it is a real operational change; factor it into your team's workflow immediately to avoid mid-year surprises.

Who Needs to Be Involved in This Migration?

This is not purely a developer task; getting the right people in the room early is vital to the success of your checkout migration.

• Ecommerce or Operations Lead — Owns the inventory of what Scripts are live and what business rules they represent.

• Finance or Pricing Team — Must validate that migrated discount logic matches existing pricing rules exactly to avoid margin leakage.

• Developer or Agency — Builds and deploys the Functions according to technical requirements.

• QA or Merchant Success — Tests the checkout experience end-to-end before go-live to ensure no customer-facing errors.

• Marketing — Flags any upcoming campaigns that rely on Scripts-based promotions, so timing does not clash with critical migration windows.

  If you are a lean team, one or two people may cover multiple roles, but the point remains: skipping any of these roles risks a broken checkout or an incorrect promotional calculation on your most critical sales days.

Shopify Functions vs. Shopify Scripts: The Key Differences at a Glance

• Language: Scripts used Ruby; Functions use JavaScript, TypeScript, or Rust via WebAssembly, reflecting a shift toward modern web standards.

• Hosting: Scripts ran on Shopify's servers in a sandboxed environment; Functions run as Wasm modules inside Shopify's modern infrastructure.

• Testability: Scripts were difficult to test locally; Functions support local testing via Shopify CLI for faster feedback loops.

• Deployment: Scripts deployed through the Script Editor in admin; Functions deploy as part of a Shopify app for better lifecycle management.

• Version control: Scripts had no native versioning; Functions are code, managed in your repository like any other asset, allowing for better rollback capabilities.

• Performance: Functions execute faster with significantly less overhead than Scripts, improving checkout speed and conversion.

• Availability: Scripts were Shopify Plus only; Functions are available to all Shopify plans, though some APIs remain Plus-exclusive for advanced merchants.

Your Migration Timeline (Work Backwards from June 30)

If June 30, 2026 is the hard stop, here is a workable timeline structure to ensure you meet the deadline without sacrificing quality.

Now through February 2026 — Discovery and Audit: Complete your Scripts inventory. Apply the Readiness Matrix. Document all business rules. Identify any third-party app dependencies. Scope the migration project and assign resources accordingly.

March through April 2026 — Build and Test: Develop Functions for your Quadrant 1 and Quadrant 2 Scripts in priority order. Build in a staging environment. Run full QA on every checkout scenario your Scripts supported.

May 2026 — Staging Validation and Soft Launch: Deploy to production for lower-risk Scripts first. Monitor behavior in the live environment. Validate in live conditions and begin migration of more complex Scripts once simpler ones are confirmed stable.

June 1–20, 2026 — Final Migration and Buffer: Complete remaining migrations. Run a full audit of your admin to confirm no active Scripts remain. Give yourself ten days of buffer before the deadline. Do not be the team scrambling on June 28 when issues arise.