Square API

connect.squareup.com · Finance

Finance Bearer Token Free Tier Payments Finance POS

Accept in-person and online payments, manage inventory, customers, and loyalty programs. Full sandbox with test card numbers. No monthly fee.

Authentication

Bearer token Free developer account at developer.squareup.com. Sandbox access token (sandbox-sq0idb-...) for testing. Pass as Authorization: Bearer YOUR_TOKEN.

Sample Requests

GET List locations

List your Square business locations.

https://connect.squareup.com/v2/locations

Hover any highlighted part to learn what it does

Headers — extra info sent with the request

Authorization	Bearer YOUR_SANDBOX_TOKEN
Square-Version	2024-01-18

curl -X GET "https://connect.squareup.com/v2/locations" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Square-Version: 2024-01-18"

import requests
headers = {
    "Authorization": "Bearer YOUR_ACCESS_TOKEN",
    "Square-Version": "2024-01-18"
}
response = requests.get(
    "https://connect.squareup.com/v2/locations",
    headers=headers,
)
print(response.json())

const url = 'https://connect.squareup.com/v2/locations';

const response = await fetch(url, {
  headers: {
    'Authorization': 'Bearer YOUR_ACCESS_TOKEN',
    'Square-Version': '2024-01-18'
  },
}); 
const data = await response.json();
console.log(data);

package main

import (
	"fmt"
	"io"
	"net/http"
)

func main() {
	targetURL := "https://connect.squareup.com/v2/locations"
	req, _ := http.NewRequest("GET", targetURL, nil)
	req.Header.Set("Authorization", "Bearer YOUR_ACCESS_TOKEN")
	req.Header.Set("Square-Version", "2024-01-18")

	client := &http.Client{}
	resp, _ := client.Do(req)
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)
	fmt.Println(string(body))
}

require "net/http"
require "json"

uri = URI("https://connect.squareup.com/v2/locations")

http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = uri.scheme == "https"

req = Net::HTTP::Get.new(uri)
req["Authorization"] = "Bearer YOUR_ACCESS_TOKEN"
req["Square-Version"] = "2024-01-18"

res = http.request(req)
puts JSON.parse(res.body)

<?php
$url = "https://connect.squareup.com/v2/locations";
$opts = ["http" => [
    "method" => "GET",
    "header" => implode("\r\n", [
        "Authorization: Bearer YOUR_ACCESS_TOKEN",
        "Square-Version: 2024-01-18"
    ]),
]];
$ctx = stream_context_create($opts);
$res = file_get_contents($url, false, $ctx);
print_r(json_decode($res, true));

POST Create payment

Create a $10.00 test payment in the sandbox.

https://connect.squareup.com/v2/payments

Hover any highlighted part to learn what it does

Headers — extra info sent with the request

Content-Type	application/json
Authorization	Bearer YOUR_SANDBOX_TOKEN
Square-Version	2024-01-18

Request Body — data you're sending

{
  "source_id": "cnon:card-nonce-ok",
  "amount_money": {
    "amount": 1000,
    "currency": "USD"
  },
  "idempotency_key": "unique-key-123"
}

curl -X POST "https://connect.squareup.com/v2/payments" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Square-Version: 2024-01-18" \
  -H "Content-Type: application/json" \
  -d '{"source_id":"cnon:card-nonce-ok","amount_money":{"amount":1000,"currency":"USD"},"idempotency_key":"unique-key-123"}'

import requests
headers = {
    "Content-Type": "application/json",
    "Authorization": "Bearer YOUR_ACCESS_TOKEN",
    "Square-Version": "2024-01-18"
}
data = {
    "source_id": "cnon:card-nonce-ok",
    "amount_money": {
        "amount": 1000,
        "currency": "USD"
    },
    "idempotency_key": "unique-key-123"
}
response = requests.post(
    "https://connect.squareup.com/v2/payments",
    headers=headers,
    json=data,
)
print(response.json())

const url = 'https://connect.squareup.com/v2/payments';

const response = await fetch(url, {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'Authorization': 'Bearer YOUR_ACCESS_TOKEN',
    'Square-Version': '2024-01-18'
  },
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
  "source_id": "cnon:card-nonce-ok",
  "amount_money": {
    "amount": 1000,
    "currency": "USD"
  },
  "idempotency_key": "unique-key-123"
}),
}); 
const data = await response.json();
console.log(data);

package main

import (
	"fmt"
	"io"
	"net/http"
	"bytes"
	"encoding/json"
)

func main() {
	targetURL := "https://connect.squareup.com/v2/payments"
	jsonData, _ := json.Marshal({"source_id":"cnon:card-nonce-ok","amount_money":{"amount":1000,"currency":"USD"},"idempotency_key":"unique-key-123"})
	req, _ := http.NewRequest("POST", targetURL, bytes.NewBuffer(jsonData))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", "Bearer YOUR_ACCESS_TOKEN")
	req.Header.Set("Square-Version", "2024-01-18")
	req.Header.Set("Content-Type", "application/json")

	client := &http.Client{}
	resp, _ := client.Do(req)
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)
	fmt.Println(string(body))
}

require "net/http"
require "json"

uri = URI("https://connect.squareup.com/v2/payments")

http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = uri.scheme == "https"

req = Net::HTTP::Post.new(uri)
req["Content-Type"] = "application/json"
req["Authorization"] = "Bearer YOUR_ACCESS_TOKEN"
req["Square-Version"] = "2024-01-18"
req["Content-Type"] = "application/json"
req.body = "{\"source_id\":\"cnon:card-nonce-ok\",\"amount_money\":{\"amount\":1000,\"currency\":\"USD\"},\"idempotency_key\":\"unique-key-123\"}"

res = http.request(req)
puts JSON.parse(res.body)

<?php
$url = "https://connect.squareup.com/v2/payments";
$opts = ["http" => [
    "method" => "POST",
    "header" => implode("\r\n", [
        "Content-Type: application/json",
        "Authorization: Bearer YOUR_ACCESS_TOKEN",
        "Square-Version: 2024-01-18",
        "Content-Type: application/json"
    ]),
    "content" => json_encode({"source_id":"cnon:card-nonce-ok","amount_money":{"amount":1000,"currency":"USD"},"idempotency_key":"unique-key-123"}),
]];
$ctx = stream_context_create($opts);
$res = file_get_contents($url, false, $ctx);
print_r(json_decode($res, true));

Postman Setup Guide

Get Postman ↗

Create a free developer account at developer.squareup.com
Get your sandbox access token from the developer dashboard
Always add Square-Version: YYYY-MM-DD header
Sandbox: use connect.squareup.com with sandbox-sq0idb-... token
Test nonces: cnon:card-nonce-ok (success), cnon:card-nonce-declined (decline)

What can you build with Square API?

Square API is a Finance API. Developers commonly use finance APIs for:

processing payments and handling transactions
building subscription and billing systems
automating invoicing and financial reporting
fraud detection and risk scoring
connecting to banking and accounting software

Bearer token. Your app exchanges credentials for a short-lived token, then sends it as an Authorization header. Tokens expire, so your code needs to handle renewal. Square API is free to use up to a usage limit, making it a low-risk choice to experiment with.

New to APIs? Read our beginner's guide

Open documentation ↗