Hi @ashlekh111! Quick clarification first: are you building this for your own store or for external merchants/clients?
If this is for your own store (sounds like it based on the external system integration you described), the process changed on January 1, 2026. You can no longer create legacy custom apps directly in the Shopify admin. Instead, you’ll create the app in the Dev Dashboard and use the client credentials grant to generate tokens.
Here’s the general workflow:
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Create your app in the Dev Dashboard
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Go to Versions → set your scopes (like
write_products) → Release -
Install the app on your store from the app’s Home tab
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Grab the Client ID and Secret from Settings
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POST to
https://{shop}.myshopify.com/admin/oauth/access_tokenwithgrant_type=client_credentials, your client ID, and client secret
One important difference is that these tokens expire after 24 hours, unlike the permanent tokens from legacy custom apps. You’ll need to refresh them by making the same request again.
If you’re building this for external merchants (not your own store), client credentials won’t work for you. You’d need to use the authorization code grant flow or token exchange instead, which involves an OAuth redirect to get merchant approval.
There’s a comprehensive thread here that walks through this entire transition: How to use Shopify’s API with custom app changes?
Can you share a bit more detail about what specifically isn’t working? Are you seeing any error messages when you try to create the app or generate tokens?