Shopify Offsite Payment extension

Topic summary

A Shopify partner is developing an offsite payment extension to allow merchants to process transactions through their custom checkout page. They serve as the payment provider with a Java-based backend handling all transactions.

Current Progress:

  • Completed first 2 steps of the official Shopify documentation
  • Stuck on configuring the extension.toml file
  • Uncertain about next steps in the development process

Key Challenge:
The developer finds the official documentation confusing and needs guidance on:

  • Proper configuration of the extension.toml file
  • How to proceed after initial setup
  • Integration approach for their separate Java API backend

The discussion remains open with no responses or solutions provided yet.

Summarized with AI on November 2. AI used: claude-sonnet-4-5-20250929.

I am trying to build a Shopify offsite Payment extension and using this documentation. I am a partner along with the shopify and I am finding myself stuck after going through the first 2 steps in the documentation as I am not sure exactly how to proceed further. I am making a extension which my merchants will install on their stores so that they can pay using my checkout page. I am the payment provider as well so I process all the transaction from my backend which is java totally different API call. So how can I proceed with the configuration file of the extension.toml file and after that how would I proceed furter? The document confuses me a lot exactly.