Square
Connect Square to track sales and refunds, send invoices and payment links, manage items, stock, customers and bookings, and see your payouts.
You end up pasting the access token of an app in your Square Developer Console. Making the app is free, takes a minute and Square reviews nothing; PopMCP works out on its own whether the token is a production or a sandbox one.
- Setup time
- 3 min
- Auth
- API credentials
- API base URL
- https://connect.squareup.com
- Rate limits
- Square publishes no fixed numbers: limits apply per application and vary by endpoint, and Square answers 429 RATE_LIMITED when one is crossed. A token connection uses your own app, so only your traffic counts against it.
Before you begin
- The Square account of the business you want to connect (any Square plan, including the free one)
- Sign-in to the Square Developer Console with that account; it is free and needs no approval
- Taking real card payments needs the Square account activated for payments (squareup.com/activation); reading sales, orders and customers does not
Get your credentials
Sign in to the Developer Console
Go to developer.squareup.com/apps and sign in with the Square account of the business you want to connect. The Applications page lists the apps on that account; a new developer account may already have one from sign-up.
Applications
Apps you build with Square APIs. Each one has its own credentials.
| Application | Created |
|---|---|
| My first appApplication | Oct 2, 2026 |
Any app on the account works. A separate one for PopMCP makes it easy to replace its token later.
Create an application for PopMCP
On the Applications page, create a new application and give it an Application name such as PopMCP (you can change it later). Square opens the new application. Creating it is free and nothing is sent for review.
Applications
Square opens the new application as soon as it is created.
Copy the Production access token
In the application's left pane choose Credentials. At the top of the page choose Production, then in the Production Access token box choose Show and copy the token (it starts with EAAA). To connect Square's test account instead, choose Sandbox at the top and copy the Sandbox Access token.
Credentials
Use these to call Square APIs for your own account.
- Application ID
- sq0idp-****K7vQ
- Production Access token
- EAAA****
The token has full access to the Square account. Treat it like a password: PopMCP stores it encrypted and never shows it to your AI.
Connect in PopMCP
Paste the token into PopMCP's Square form and click Connect Square. PopMCP checks it with Square, finds out whether it is a production or a sandbox token, and shows the business it belongs to with its active locations.
Connect in PopMCP
Open your workspace, choose Square in the marketplace, and fill in the connect dialog:
| Field | What to enter |
|---|---|
| Access tokensecret | At developer.squareup.com/apps, sign in with your Square account, create an app (any name, free) or open one, choose Credentials, keep Production selected at the top, then Show and copy the Access token. For Square's test account use the Sandbox access token instead. Stored encrypted.Encrypted with AES-256-GCM on save and never shown again. |
PopMCP verifies the credential against Square immediately. On success the connection flips to Verified and its MCP tools are provisioned.
Verify it worked
PopMCP shows the Square connector as Connected with the business name (marked sandbox for a sandbox token) and how many active locations the business has.
Troubleshooting
Square did not accept this access token
Why: Only part of the token was copied, it was replaced in the Developer Console, or it belongs to a different Square account.
Fix: Open the application's Credentials page, choose Show next to the Production Access token and copy all of it again.
The form says it is an Application ID or Application secret
Why: The Application ID (sq0idp-) sits on the same page, and the Application secret (sq0csp-) on the OAuth page; neither is the token.
Fix: Copy the value in the Production Access token box (or the Sandbox Access token box) instead.
Nothing with that id was found
Why: Production and the sandbox are separate: a payment, order or customer id from one does not exist in the other.
Fix: Check whether the connection is the sandbox (its name ends in sandbox), and connect the production token for real business data.
Card payments are refused on a new Square account
Why: The Square account is not activated for payments yet.
Fix: Activate it at squareup.com/activation, then try again. Recording cash or other outside payments works without it.
Creating a booking is refused
Why: Writing bookings for any team member through an app needs Square Appointments Plus or Premium.
Fix: Upgrade the Appointments plan in the Square Dashboard, or create the booking in Square Appointments directly.
Reference
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