Shopify Functions Development
For AU merchants who need custom discount, shipping, payment and cart logic that runs natively at checkout, with no Scripts, no third-party app tax and no checkout slowdown.
When off-the-shelf discount and shipping apps stop fitting
Shopify Scripts are retiring and generic apps rarely model real promotional logic. Functions let us build the exact rule you need, run it server-side at checkout, and keep it fast.
Scripts are being retired
Tiered, bundle and cart-value logic built on Shopify Scripts needs migrating to Functions before it stops working.
Apps cannot model your promo
Buy-X-get-Y across specific collections, spend thresholds, member pricing. The app store forces you to bend the rule to fit the app.
Stacking discounts erode margin
Multiple codes and automatic discounts collide, over-discount carts and eat margin without clear control over precedence.
Shipping logic is too blunt
Native rate rules cannot hide, rename or reorder methods by cart contents, postcode or customer tag the way you need.
Payment methods need gating
You want to hide COD for high-risk carts or show B2B terms only to approved accounts, which native settings cannot express.
Bundles and gifts feel bolted on
Automatic free gifts and bundle pricing added by apps show inconsistently and slow the cart and checkout down.
Scope at a glance
A typical Functions engagement, and where the line sits.
| Included | Your side | Out of scope | |
|---|---|---|---|
| Discount logic | Design, build, test, deploy Functions | Confirm the promo rules and edge cases | Ongoing campaign scheduling in-app |
| Shipping & payment | Delivery and payment customisation Functions | Carrier accounts and rate data | Third-party carrier app contracts |
| Merchant control | Metafield inputs so staff can adjust values | Naming the values you want editable | New logic branches added later |
| Migration | Port existing Scripts to Functions | Access to current Scripts and rules | Rebuilding unrelated legacy apps |
Is this the right fit?
A good fit if
- You are on Shopify Plus, or an advanced plan, and need checkout-native logic
- You are migrating discount or shipping logic off retiring Shopify Scripts
- Your promotions are too specific for an off-the-shelf discount app
- You want to cut recurring app fees by owning the logic outright
- You need discount, shipping or payment rules that survive a Plus checkout upgrade
Not a fit if
- A standard automatic discount or code covers your needs already
- You want a full custom checkout UI (that is Checkout Extensibility)
- You need logic outside checkout, such as an embedded admin app or external sync
- You are not on a plan that supports Shopify Functions
What we build with Shopify Functions
Each Function is a small, server-side program that Shopify runs natively at checkout. We build, test and deploy the ones your store needs.
Discount & pricing Functions
- Product, order and shipping discount logic
- Tiered and cart-value thresholds
- Buy-X-get-Y across specific collections
- Member, wholesale and tag-based pricing
- Discount stacking and precedence control
- Automatic free gifts and bundle pricing
Checkout logic Functions
- Hide, rename and reorder delivery methods
- Custom shipping rates by cart, postcode or tag
- Hide or gate payment methods by risk or account
- Cart and checkout validation rules
- Cart transforms for bundles and merged lines
- Local pickup and delivery customisation
Build & delivery
- Rust or JavaScript Functions on the Shopify CLI
- Scripts-to-Functions migration
- Merchant-editable inputs via metafields
- Automated tests and staging validation
- Versioned deploys with rollback
- Handover docs and admin configuration
How a Functions build runs
Discovery to deployment, typically 2 to 5 weeks depending on how many Functions and how complex the rules are.
Discovery
We map every rule, edge case and precedence question, and confirm which belong in Functions versus native settings.
Logic design
We spec each Function, its inputs, outputs and merchant-editable values, and agree acceptance criteria with you.
Build
We develop the Functions in Rust or JavaScript on the Shopify CLI, with metafield inputs so your team can adjust values later.
Test
Automated tests plus manual checkout runs across carts, tags and postcodes on a development store.
Staging review
You validate the logic against real scenarios and sign off before anything touches production.
Deploy
Versioned release to your live store, watched through the first live orders with rollback ready.
Handover
Documentation, admin walkthrough and a short support window so your team owns the logic.
Quality and controls
Checkout logic touches revenue, so we treat it that way.
- Automated test coverage on every Function branch
- Edge-case matrix across carts, tags, postcodes and quantities
- Margin and stacking checks so discounts cannot compound unintentionally
- Versioned deploys with instant rollback
- No impact on checkout speed or Plus checkout certification
- Merchant-editable inputs documented for your team
Investment
Typical AUD ranges, scoped precisely after discovery. Price depends on the factors below.
Single Function
One focused discount, shipping or payment rule, tested and deployed.
Multi-Function suite
Several related Functions, stacking control and merchant inputs.
Scripts migration
Port and rebuild retiring Scripts as Functions, with parity testing.
Frequently asked questions
Related services
Need checkout logic that fits your rules?
Tell us the discount, shipping or payment rule you are wrestling with, or the Scripts you need to migrate. We will scope the Functions in a short call.
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