Square

Overview

Square’s API covers payments, orders, inventory, customers, and more for physical and online businesses. Auth is a personal access token (or OAuth for third-party apps) — requests without one return 401 (verified).

Quick Start

List catalog (replace YOUR_TOKEN):

curl "https://connect.squareup.com/v2/catalog/list" \
  -H "Authorization: Bearer YOUR_TOKEN"

{ "objects": [], "cursor": "..." }

Create an order:

curl -X POST "https://connect.squareup.com/v2/orders" \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -H "Square-Version: 2026-08-19" \
  -d '{"idempotency_key": "unique-key", "order": {"location_id": "LOCATION_ID"}}'

Authentication

• Personal access token: Developer Dashboard → Applications → Access Tokens (production).
• OAuth flow for third-party apps (Authorization Code + PKCE).
• Send as Authorization: Bearer YOUR_TOKEN (missing → 401, verified).
• Always set the Square-Version header to a dated API version.

Rate Limits & Notes

• Rate limits are per application and endpoint class (see docs).
• Endpoints: /v2/catalog, /v2/orders, /v2/payments, /v2/customers, /v2/inventory, /v2/locations.
• Sandbox mode: connect.squareupsandbox.com with sandbox tokens for testing.
• idempotency_key is required on write endpoints.

FAQ

Is Square API free? No monthly fee; you pay per-transaction fees. API access is free.

How do I get a token? Developer Dashboard → Applications → Access Tokens.

What’s the sandbox? connect.squareupsandbox.com + sandbox tokens for testing without real charges.