Checkout Extensibility & Migration
What does a Checkout Extensibility migration actually cost for a mid-market Shopify Plus store with 5-10 custom checkout integrations?
No published figure exists. Here is the honest answer
No published price exists for a Checkout Extensibility migration of 5 to 10 integrations, because cost follows each integration, not the store. Shopify's Partner Directory lists 2,271 checkout upgrade partners, and 14 of the 16 on its first page show "Contact for pricing" (Shopify Partner Directory, October 2026). So price each integration's replacement, then the program around it.
- Published market price
- None for a 5 to 10 integration migrationShopify's Partner Directory lists 2,271 checkout upgrade partners; on page one, 14 of 16 show Contact for pricing and two show starting prices of $500 and $1,000 (October 2026).Source: Shopify Partner Directory (Checkout upgrade)
- Record estimate, program length
- 8 to 14 weeks end to endThe checkout extensibility record's illustrative estimate for a real Scripts footprint; it adds that one margin-critical Function can ship in 2 to 3 weeks (Deploi decision record, October 2026).Source: Deploi Build vs. Buy (Build or Buy Your Checkout Extensibility Upgrade on Shopify Plus?)
- Record estimate, upkeep
- About 15 to 20% of build cost a yearAfter cutover: API version updates, extension changes and a pixel re-check at each checkout upgrade; the checkout extensibility record's illustrative estimate (October 2026).Source: Deploi Build vs. Buy (Build or Buy Your Checkout Extensibility Upgrade on Shopify Plus?)
- Record estimate, app path
- About $14,900 to $39,000 over three yearsRenting parity apps for the generic rules: $500 to $3,000 to set up, then $14,400 to $36,000; the checkout extensibility record's illustrative estimate, not a quote (October 2026).Source: Deploi Build vs. Buy (Build or Buy Your Checkout Extensibility Upgrade on Shopify Plus?)
Deploi’s call
No honest per-store price exists, so price a Checkout Extensibility migration per integration and refuse to quote the store. Any fixed quote issued before the parity map, the written list of every rule the old checkout ran, is a quote for a scope neither party has seen. It will be renegotiated in week four.
BuildCommission the full program when
- Two or more integrations have no like-for-like Shopify Function, the code Shopify runs at checkout, and no vendor extension.
- The rules touch margin. Deploi's checkout extensibility record scores real Scripts-era logic BUILD (Deploi decision record, October 2026).
- A written parity map exists, so agency quotes price the same scope.
CustomizeRent apps for the generic rules when
- An app's settings page expresses every rule you keep.
- The record's app path fits the budget: about $500 to $3,000 to set up and $14,400 to $36,000 over three years, illustrative (Deploi decision record, October 2026).
- You commission only the audit and a pixel check, the record's CUSTOMIZE path for a light Scripts footprint (Deploi decision record, October 2026).
Basis: Build or Buy Your Checkout Extensibility Upgrade on Shopify Plus?, our Build vs. Buy decision record, scored BUILD.
Why is there no published price for a 5 to 10 integration migration?
There is no published price because two Shopify Plus stores with the same integration count can need very different work. "Eight custom checkout integrations" can mean a shipping rule with a like-for-like Shopify Function, or a bespoke insurance widget behind a partner's application programming interface (API). The market shows it: Shopify's Partner Directory lists 2,271 checkout upgrade partners, and 14 of the 16 on its first page show "Contact for pricing" (Shopify Partner Directory, October 2026). The other two show self-set starting prices of $500 and $1,000, which price a partner's entry service, not your checkout. Which checkout surfaces each Shopify plan lost sets out what there is to replace.
Is a Checkout Extensibility migration still ahead of a Plus store in October 2026?
No: on Shopify Plus the old checkout code has already stopped, so the work is a rebuild of what stopped rather than a migration ahead of a deadline. Shopify Scripts stopped on 30 June 2026 (Shopify Help Center, October 2026). Automatic upgrades reached the Thank you and Order status pages in January 2026 (Shopify Help Center, October 2026). So each quote now prices restoring a rule or a tag, and the first job is listing what stopped. Every week spent scoping is a week the store trades without that rule, so scope fast and price per item.
What does each type of checkout integration cost to replace?
Each integration's cost follows its replacement path, and two types carry most of the risk: discount logic with no like-for-like Shopify Function, the code Shopify runs at checkout, and third-party widgets that wait on a vendor. App blocks and pixels, the other two paths, are mostly configuration.
| Integration type | Replacement path | Relative cost |
|---|---|---|
| Discount or shipping rule with a like-for-like Function | Custom Shopify Function | Low to medium |
| Discount logic with no one-to-one Function | Redesign the rule with merchandising, then build | High |
| Post-purchase upsell | App block on the Thank you page | Low, plus a subscription |
| Analytics and conversion tags | App pixel or custom pixel | Low to medium |
| Custom fields at checkout | Checkout user interface (UI) extension, Plus-only on the Information, Shipping and Payment steps | Medium |
| Partner widget with its own application programming interface (API) | The vendor's own extension, if one exists | Unbounded |
Tags are cheap to move and costly to get wrong, so budgeting for a tracking app is a separate decision.
What does Deploi's decision record estimate for the full program?
Deploi's checkout extensibility record estimates 8 to 14 weeks for the full program, from audit to staged cutover, for a real Scripts footprint (Deploi decision record, October 2026). The record puts upkeep after cutover at about 15 to 20% of build cost a year, with no subscription line. The record also prices renting apps for the generic rules instead, so a store can see what the build has to beat.
| Path | Time | Record estimate (illustrative) |
|---|---|---|
| Build the full program | 8 to 14 weeks | Upkeep of 15 to 20% of build cost a year |
| Rent apps for the generic rules | Days | About $14,900 to $39,000 over three years, setup included |
A Scripts port on its own is narrower: the three-year build-versus-app arithmetic runs on the Scripts-to-Functions record, and what an agency-built discount Function costs prices one rule.
What moves the price most?
Undocumented rules move the price most, because someone has to work out what an old rule did before anyone can rebuild it. Deploi's decision records name four drivers, ranked here by Deploi's judgment:
- Rules with no owner. The checkout extensibility record calls them orphan rules and says to "budget archaeology time before rewrite time" (Deploi decision record, October 2026).
- A parity test, a replay of old carts against the new code. The Scripts-to-Functions record says skipping it "converts silent Script death into silent Function drift" (Deploi decision record, October 2026).
- App stacking. The checkout extensibility record warns that app parity "adds two or three subscriptions that never stop billing", so price the stack, not the app (Deploi decision record, October 2026).
- Scope creep. The checkout extensibility record says to "hold the parity map as the contract and push improvements to phase two" (Deploi decision record, October 2026); the parity map is the list of rules to restore.
Why some migrations went smoothly and others did not shows how the same drivers play out on the schedule.
When is the honest cost zero?
The honest cost is zero when the audit finds nothing to rebuild, and Shopify already generates the first scoping document for free. The Shopify Scripts customizations report under Apps > Script Editor lists the Scripts that were active before 30 June 2026, and it exports as a comma-separated values (CSV) file (Shopify Help Center, October 2026). Deploi's checkout extensibility record says a Scripts-deprecation audit "takes a day", and one Deploi audit came back with zero exposure (Deploi decision record, October 2026).
Deploi’s point of view
Our own position, from building on Shopify. Kept apart from the sourced facts above.
- Where we disagree
- The category prices this as a technical migration with a per-integration rate. A meaningful share of the effort is a merchandising conversation about which rules should survive at all, and that time belongs in the estimate rather than hidden in contingency.
- What we ask for first (our judgment, not a measurement)
- The variance between two superficially identical Plus stores is almost entirely explained by how many checkout rules nobody can currently explain. That count, not the integration count, is the number worth asking for on the first call.
- What this page adds
- The parent dates which checkout surfaces each plan lost. This page prices the rebuild: why no per-store price exists, the replacement path and risk for each integration type, the decision records' timelines and app-path costs, and the drivers that move a quote.
Decision records behind this answer
When this answer changes
- Shopify ships Function APIs that cover rules which today need a redesign, which moves those integrations down the cost table.
- Shopify retires the Script Editor app or its Scripts customizations report.
- Deploi's checkout extensibility or Scripts-to-Functions record changes its timeline, upkeep share or app-path figures.
- A checkout app category consolidates and a parity app this page counts on leaves the App Store.
Related questions
This follows from Does the checkout.liquid shutdown affect stores on every Shopify plan, or only Shopify Plus stores?
- Do we need to budget for a tracking-app plan upgrade (e.g., to a server-side tier) at the same time we migrate to Checkout Extensibility?
A tracking-app upgrade belongs in the migration budget only when purchase tracking sat in the Additional scripts box or a script tag, because both stopped on the Thank you and Order status pages (shopify.dev, October 2026).
- Once we factor in ongoing maintenance (not just the initial build), does a custom Shopify Function ever actually beat a third-party discount app's subscription cost over 2-3 years?
A custom Shopify Function, code Shopify runs at checkout, does not beat a discount app's three-year cost on one common rule.
- What does it realistically cost to have an agency build a custom Shopify Function for one discount use case?
An agency-built Shopify Function, the custom code Shopify runs at checkout, has no published market rate for one discount rule.
- Why do some Shopify Plus merchants report their Checkout Extensibility migration went smoothly while others describe it as their worst platform experience of the year?
Checkout Extensibility migration difficulty tracks one variable, not store size: how many customizations depend on another company's release schedule.
Sources
Every figure on this page traces to one of these. Official and vendor pages are checked on the date shown; Deploi records are our own published decisions.
- Shopify Partner Directory, Checkout upgrade
- Shopify developer docs, About Shopify Functions
- Shopify developer docs, Checkout UI extensions
- Shopify Help Center, Transitioning from Shopify Scripts to Shopify Functions
- Shopify Help Center, Google Tag Manager
- Shopify Help Center, Customization options for Thank you and Order status pages
- Deploi Build vs. Buy, Build or Buy Your Checkout Extensibility Upgrade on Shopify Plus?
- Deploi Build vs. Buy, Should You Build or Buy Your Shopify Scripts-to-Functions Migration?