0n3
MCP servers · Square · connector · GPT action

Connect ChatGPT to Square

One line gives ChatGPT your Square account as tools: 57 endpoints, payments, customers, orders, called with your own connection. No key in the prompt, a receipt for every call, revoke ChatGPT's access alone any time.

Get the line for ChatGPTConnect Square first

Three steps

  1. Create a free 0n3 account and connect Square. Paste a key or sign in; it lands in your vault, encrypted.
  2. Install 0n3 into ChatGPT. A custom connector in Developer mode, or an Action on a custom GPT from the OpenAPI spec.
  3. Ask ChatGPT: whoami. Then: "Create a payment in Square".
Custom connector (needs Developer mode)
  1. Settings → Connectors (or Apps) → Advanced → Developer mode on
  2. Create → name 0n3 · MCP server URL https://0n3.app/mcp · Authentication: OAuth
  3. Finish the sign-in with your 0n account
  4. Enable the connector in a chat and ask: "whoami"

ChatGPT connectors cannot send a static header, so 0n3 signs you in through its OAuth door (dynamic client registration is on).

The line above carries a placeholder; 0n3.app/install mints a real key named for ChatGPT and fills it in.

What ChatGPT can then do in Square

Payments · Process payments, refunds, and completions4
Create a paymentPOST /payments
List paymentsGET /payments
Get a paymentGET /payments/{paymentId}
Complete a paymentPOST /payments/{paymentId}/complete
Customers · Full customer directory management6
Create a customerPOST /customers
List customersGET /customers
Get a customerGET /customers/{customerId}
Update a customerPUT /customers/{customerId}
Delete a customerDELETE /customers/{customerId}
Search customersPOST /customers/search
Orders · Create, manage, and pay orders5
Create an orderPOST /orders
Search ordersPOST /orders/search
Get an orderGET /orders/{orderId}
Update an orderPUT /orders/{orderId}
Pay an orderPOST /orders/{orderId}/pay
Catalog · Product catalog lifecycle5
Create a catalog objectPOST /catalog/object
List catalogGET /catalog/list
Search catalogPOST /catalog/search
Update a catalog objectPOST /catalog/object
Delete a catalog objectDELETE /catalog/object/{objectId}
Inventory · Inventory tracking and transfers3
Get an inventoryPOST /inventory/counts/batch-retrieve
Adjust inventoryPOST /inventory/changes/batch-create
Transfer inventoryPOST /inventory/transfers/batch-create
Invoices · Create and send invoices6
Create an invoicePOST /invoices
List invoicesGET /invoices
Get an invoiceGET /invoices/{invoiceId}
Update an invoicePUT /invoices/{invoiceId}
Publish an invoicePOST /invoices/{invoiceId}/publish
Cancel an invoicePOST /invoices/{invoiceId}/cancel

All 57 Square endpoints →

Square in other AI clients

Claude Code + SquareMCP server + skillClaude (desktop & claude.ai) + SquareconnectorCodex CLI + SquareMCP serverGemini CLI + SquareMCP serverCursor + SquareMCP serverVS Code (Copilot) + SquareMCP serverWindsurf + SquareMCP server

ChatGPT with other apps

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