Shopify Winter ’26 Edition: what changed for app developers

Shopify published the developer side of its Winter ’26 Edition, code-named “Renaissance”, on December 10, 2025. It set the direction the Spring and Fall Editions have followed since: apps are no longer only screens in the admin, they are also tools that assistants and other surfaces can use. As a studio that builds and runs its own apps (CartGift, Trustify and CommerceOps), here is how we read it.

Sidekick app extensions

Apps can now expose their data and actions to Sidekick, Shopify’s assistant in the admin. A merchant can ask Sidekick a question and get an answer that uses an app’s data, or ask it to do something the app can do.

Our take: this changes what “good app UX” means. Merchants will increasingly meet an app through a question rather than through its settings page. Two things follow for app developers:

• Name and describe actions carefully. If an action is called “sync” with no description, Sidekick cannot know when to use it. Clear, narrow actions work best.
• Be strict about what an action may change. An action that edits prices or deletes data should ask for confirmation and log what it did. The merchant is trusting two layers now, Sidekick and your app.

For merchants choosing apps, it is a fair question to ask a vendor: “does your app work with Sidekick, and what can it do there?”

Shopify Catalog for every developer

Shopify Catalog, the structured index of products across Shopify stores, started rolling out to every developer through MCP tools and a REST API. Checkout tools for agents were in preview for selected partners at the time.

Our take: this is the foundation for the agentic commerce work that followed in 2026. For most app developers it is not something to build on directly yet, but it is a strong signal: product data quality is becoming a feature. Apps that help merchants enrich and structure product data have a growing job to do. We wrote more about the merchant side in Agentic commerce on Shopify.

Checkout Kit for the web

Checkout Kit, previously known from mobile apps, came to the web as a JavaScript library that opens Shopify checkout in a popup or inline on any site.

Our take: useful for brands that sell from a site that is not a Shopify storefront, such as a content site, a booking flow or a configurator built on another stack. You keep Shopify checkout, with its payments, discounts and extensions, without moving the whole site to Shopify.

Shop Minis SDK out of beta

The Shop Minis SDK, for building experiences inside the Shop app, left beta and is ready for production, with a target of three days for submission reviews.

Our take: worth a look for brands with a loyal Shop app audience and something interactive to offer, such as a quiz, a drop or a configurator. For most stores the storefront is still the better place to invest first.

A development platform built for assistants

Shopify described its developer platform as “AI-native”: the Dev MCP server helps with scaffolding apps, writing GraphQL and building UI extensions from inside a code editor, and the Dev Dashboard gained a playground for building agent flows.

Our take: these tools are good at the boring parts, like looking up the right GraphQL field or the current shape of an extension target. They do not replace knowing the platform. Every API version still changes things, Function limits still apply, and review still matters before anything touches a merchant’s checkout.

What app teams should do

1. List the three actions merchants use most in your app and design them as clear, safe Sidekick actions.
2. Audit what your app writes to stores: prices, metafields, tags. Make sure every write is logged and reversible.
3. If your app touches product data, look at how it can help merchants get listed and described well in Shopify Catalog.

If you are a merchant who needs a custom app or a Function for something no app does, that is exactly the work we do: see Shopify app development.

Sources

• Winter ’26 Edition for developers (Shopify newsroom, December 10, 2025)
• Shopify Editions Winter ’26 (Shopify)