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Guide

How to integrate Square payments

Follow these steps in Evonx to add Square payments for online or in-person checkout. Use this when POS or invoicing flows prefer Square over Stripe.

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Step-by-step

Create a Square application

Generate sandbox credentials and decide between online payments and Terminal APIs.

Store access tokens securely

Keep Square secrets in server env vars; rotate and scope by location when multi-store.

Implement payment creation

Create payments server-side with idempotency keys tied to your order or invoice IDs.

Handle webhooks

Verify Square webhook signatures and update order/payment status idempotently.

Add refunds and voids

Expose operator tools that call Square refund APIs and mirror state in your database.

Preview in sandbox

Run successful, declined, and refund cases against sandbox before production merge.

Outcome

Square payment integration with secure charges, webhooks, and refunds you can operate in production.

Related resources

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FAQ

Square vs Stripe—when to choose Square?

Choose Square when you already use Square hardware or seller tooling. Choose Stripe for broader SaaS billing patterns.

How do locations map to my app?

Store Square location IDs on your store/site records and always pass the correct location on payment APIs.

Are idempotency keys required?

Yes for create payment calls—reuse the same key on retries to prevent double charges.

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